Patent Publication Number: US-2020291879-A1

Title: Systems and methods for diagnosing ejector system degradation for dual-path purge engine systems

Description:
FIELD 
     The present description relates generally to methods and systems for conducting engine-off diagnostics on a vehicle ejector system of a dual-path purge engine system. 
     BACKGROUND/SUMMARY 
     Vehicles may be fitted with evaporative emission control systems such as onboard fuel vapor recovery systems. Such systems capture and prevent release of vaporized hydrocarbons to the atmosphere, for example fuel vapors generated in a vehicle gasoline tank during refueling. Specifically, the vaporized hydrocarbons (HCs) are stored in a fuel vapor canister packed with an adsorbent which adsorbs and stores the vapors. At a later time, when the engine is in operation, the evaporative emission control system allows the vapors to be purged into the engine intake manifold for use as fuel. The fuel vapor recovery system may include one more check valves, ejector(s), and/or controller actuatable valves for facilitating purge of stored vapors under boosted or non-boosted engine operation. Regulations require that hardware pertaining to the fuel vapor recovery system be regularly assessed for the presence or absence of degradation. 
     Toward this end, U.S. Pat. No. 7,900,608 discloses diagnosing fuel vapor recovery system hardware during boosted engine operation. However, the inventors herein have recognized potential issues with such methodology. Specifically, the methodology relies upon monitoring pressure changes in the fuel vapor recovery system during boosted engine operation. However, depending on fuel tank size and fuel fill level, there may be varying timeframes for which boosted engine operation can pressurize or evacuate the fuel vapor recovery system in order to robustly assess such pressure changes to indicate the presence or absence of degradation. For hybrid electric vehicles, engine run-time may be infrequent, thus limiting opportunity to conduct such diagnostics. Furthermore, it is additionally recognized that boosted engine operation duration may frequently be less than the time frame to sufficiently pressurize or evacuate the fuel vapor recovery system, thus undesirably leading to aborted diagnostic routines and/or inconclusive results. 
     Accordingly, discussed herein, the inventors have developed systems and methods to address the above-mentioned issues. In one example, a method comprises while an engine of a vehicle is off and when a set of predetermined conditions are met, directing a positive pressure with respect to atmospheric pressure into an ejector system in order to communicate a negative pressure with respect to atmospheric pressure on a fuel system and an evaporative emissions system, and indicating that the ejector system is degraded responsive to the negative pressure not reaching a vacuum build threshold. In this way, when such an ejector system diagnostic cannot be conducted during an engine-on condition, the diagnostic may be conducted during engine-off conditions, which may increase completions rates for such a diagnostic and which may in turn reduce opportunities for release of undesired emissions to atmosphere. 
     As one example, directing the positive pressure into the ejector system may comprise commanding a routing valve to a second routing valve position to selectively couple a pump to the ejector system by way of an engine-off boost conduit. Alternatively, commanding the routing valve to a first routing valve position may selectively couple the pump to a vent line stemming from a fuel vapor storage canister positioned in the evaporative emissions system. 
     The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. 
     It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic diagram of a multi-path fuel vapor recovery system of a vehicle system where an ELCM pump is fluidically coupled to a fuel vapor storage canister. 
         FIG. 2  shows an alternative schematic diagram of the multi-path fuel vapor recovery system of  FIG. 1 , where the ELCM pump is fluidically coupled to an ejector system. 
         FIG. 3A  shows a schematic depiction of an evaporative level check module (ELCM) in a configuration to perform a reference check. 
         FIG. 3B  shows a schematic depiction of an ELCM in a configuration to evacuate a fuel system and evaporative emissions system. 
         FIG. 3C  shows a schematic depiction of an ELCM in a configuration that couples a fuel vapor canister to atmosphere. 
         FIG. 3D  shows a schematic depiction of an ELCM in a configuration to pressurize a fuel system and evaporative emissions system. 
         FIGS. 4A-4B  show a schematic depiction of an electronic circuit configured to reverse the spin orientation of an electric motor. 
         FIG. 5  depicts a high-level example method for conducting diagnostics on an engine-off boost conduit that routes pressurized air from the ELCM to the ejector system. 
         FIG. 6  depicts a high-level example method for diagnosing a third check valve configured to prevent positive pressure from entering into an intake passage of an engine from the engine-off boost conduit of  FIG. 5 . 
         FIG. 7  depicts a high-level example method for conducting diagnostics on the fuel system and/or evaporative emissions system that relies on vacuum generated by an engine that is combusting air and fuel. 
         FIG. 8  depicts a high-level example method for using the ELCM to diagnose whether a canister purge valve is stuck closed, and whether a first check valve and/or a second check valve is stuck open. 
         FIG. 9  depicts a high-level example method for conducting a diagnostic to assess functionality of an ejector system during engine-off conditions. 
         FIG. 10  depicts a high-level example method for conducting a diagnostic to assess functionality of an ejector system during conditions where the engine is combusting air and fuel. 
         FIG. 11  depicts a high-level example method for conducting a purging operation of a fuel vapor storage canister that relies on engine intake manifold vacuum. 
         FIG. 12  depicts an example timeline for conducting the diagnostics on the engine-off boost conduit according to the method of  FIG. 5 . 
         FIG. 13  depicts an example timeline for diagnosing the third check valve according to the method of  FIG. 6 . 
         FIG. 14  depicts an example timeline for diagnosing whether the canister purge valve is stuck closed and whether the first check valve and/or second check valve is stuck open, according to the method of  FIG. 8 . 
         FIG. 15  depicts an example timeline for conducting the diagnostic to assess functionality of the ejector system during engine-off conditions, according to the method of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description relates to systems and methods for conducting a diagnostic to assess functionality of an ejector system for a vehicle dual-path purge system, where the diagnostic does not rely on engine operation, or in other words, is independent of the engine combusting air and fuel. The diagnostic is based on an ability of an evaporative level check monitor (ELCM) pump to selectively be fluidically coupled to a fuel vapor storage canister under one condition, and to be fluidically coupled to the ejector system by way of an engine-off boost (EOBC) conduit under another condition. When the ELCM pump is fluidically coupled to the ejector system, the ELCM may be operated in a positive-pressure mode to supply pressurized air to the ejector system, and a resultant vacuum generated via the ejector system may be relied upon for ascertaining presence or absence of ejector system function. Accordingly,  FIG. 1  depicts the dual-path purge system in a first configuration with the ELCM fluidically coupled to the fuel vapor storage canister. Alternatively,  FIG. 2  depicts the dual-path purge system in a second configuration with the ELCM fluidically coupled to the engine-off boost conduit.  FIGS. 3A-3D  depict various ways in which the ELCM pump can operate, including a vacuum-mode and a pressure-mode of operation. To enable operation in either the vacuum-mode or the pressure-mode, an H-bridge is employed, as depicted at  FIGS. 4A-4B . 
     In order to use the ELCM pump to diagnose whether the ejector system is degraded during engine-off conditions, a number of conditions may have to first be met in order to pinpoint degradation as stemming from the ejector system and not from other aspects of the dual-path purge system. One such condition is that the EOBC (including an EOBC valve) is not degraded. Accordingly a diagnostic pertaining to whether or not the EOBC is degraded, is depicted at  FIG. 5 . Another such condition is that the third check valve (CV3) configured to prevent positive pressure with respect to atmospheric pressure from entering into the intake passage of the engine from the EOBC is not stuck open. Accordingly, methodology for determining whether the CV3 is stuck open is depicted at  FIG. 6 . Yet another such condition is that there is no indicated degradation stemming from the fuel system and/or evaporative emissions system and that a canister purge valve (CPV) and a fuel tank isolation valve (FTIV) are not stuck closed. Accordingly methodology for assessing such parameters is depicted at  FIG. 7 , where such methodology relies on intake manifold vacuum under conditions of engine operation. Still another condition for enabling entry into the ejector system diagnostic may include an indication that the first check valve (CV1) is not stuck open. Accordingly,  FIG. 8  depicts methodology for assessing whether the CV1 is potentially stuck open, and further includes methodology for determining presence or absence of undesired evaporative emissions stemming from the fuel system and/or evaporative emissions system and whether the CPV (and in some examples the FTIV) is stuck closed. Yet another such condition may comprise an indication that the fuel vapor storage canister is substantially clean (e.g. 5% loaded or less), and accordingly a method for purging the canister that relies on engine intake manifold vacuum is depicted at  FIG. 11 . 
     Provided conditions are met for conducting the engine-off diagnostic to ascertain presence or absence of degradation stemming from the ejector system, the methodology of  FIG. 9  may be used. However, it is also recognized that there may in some examples be opportunity to conduct a similar diagnostic that relies on boosted engine operation, and accordingly, such a method is depicted at  FIG. 10 . 
       FIG. 12  depicts an example timeline illustrating the methodology of  FIG. 5 ,  FIG. 13  depicts an example timeline illustrating the methodology of  FIG. 6 ,  FIG. 14  depicts an example timeline illustrating the methodology of  FIG. 8 , and  FIG. 15  depicts an example timeline illustrating the methodology of  FIG. 9 . 
     Turning to the figures,  FIG. 1  shows a schematic depiction of a vehicle system  100 . The vehicle system  100  includes an engine system  102  coupled to a fuel vapor recovery system (evaporative emissions control system)  154  and a fuel system  106 . The engine system  102  may include an engine  112  having a plurality of cylinders  108 . In some examples, the vehicle system may be configured as a hybrid electric vehicle (HEV) or plug-in HEV (PHEV), with multiple sources of torque available to one or more vehicle wheels  198 . In the example shown, vehicle system  100  may include an electric machine  195 . Electric machine  195  may be a motor or a motor/generator. Crankshaft  199  of engine  112  and electric machine  195  are connected via a transmission  197  to vehicle wheels  198  when one or more clutches  194  are engaged. In the depicted example, a first clutch is provided between crankshaft  199  and electric machine  195 , and a second clutch is provided between electric machine  195  and transmission  197 . Controller  166  may send a signal to an actuator of each clutch  194  to engage or disengage the clutch, so as to connect or disconnect crankshaft  199  from electric machine  195  and the components connected thereto, and/or connect or disconnect electric machine  195  from transmission  197  and the components connected thereto. Transmission  197  may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various manners including as a parallel, a series, or a series-parallel hybrid vehicle. 
     Electric machine  195  receives electrical power from a traction battery  196  to provide torque to vehicle wheels  198 . Electric machine  195  may also be operated as a generator to provide electrical power to charge traction battery  196 , for example during a braking operation. 
     The engine  112  includes an engine intake  23  and an engine exhaust  25 . The engine intake  23  includes a throttle  114  fluidly coupled to the engine intake manifold  116  via an intake passage  118 . An air filter  174  is positioned upstream of throttle  114  in intake passage  118 . The engine exhaust  25  includes an exhaust manifold  120  leading to an exhaust passage  122  that routes exhaust gas to the atmosphere. The engine exhaust  122  may include one or more emission control devices  124 , which may be mounted in a close-coupled position in the exhaust. One or more emission control devices may include a three-way catalyst, lean NOx trap, diesel particulate filter, oxidation catalyst, etc. It will be appreciated that other components may be included in the vehicle system, such as a variety of valves and sensors, as further elaborated below. 
     Throttle  114  may be located in intake passage  118  downstream of a compressor  126  of a boosting device, such as turbocharger  50 , or a supercharger. Compressor  126  of turbocharger  50  may be arranged between air filter  174  and throttle  114  in intake passage  118 . Compressor  126  may be at least partially powered by exhaust turbine  54 , arranged between exhaust manifold  120  and emission control device  124  in exhaust passage  122 . Compressor  126  may be coupled to exhaust turbine  54  via shaft  56 . Compressor  126  may be configured to draw in intake air at atmospheric air pressure into an air induction system (AIS)  173  and boost it to a higher pressure. Using the boosted intake air, a boosted engine operation may be performed. 
     An amount of boost may be controlled, at least in part, by controlling an amount of exhaust gas directed through exhaust turbine  54 . In one example, when a larger amount of boost is requested, a larger amount of exhaust gases may be directed through the turbine. Alternatively, for example when a smaller amount of boost is requested, some or all of the exhaust gas may bypass turbine via a turbine bypass passage as controlled by wastegate (not shown). An amount of boost may additionally or optionally be controlled by controlling an amount of intake air directed through compressor  126 . Controller  166  may adjust an amount of intake air that is drawn through compressor  126  by adjusting the position of a compressor bypass valve (not shown). In one example, when a larger amount of boost is requested, a smaller amount of intake air may be directed through the compressor bypass passage. 
     Fuel system  106  may include a fuel tank  128  coupled to a fuel pump system  130 . The fuel pump system  130  may include one or more pumps for pressurizing fuel delivered to fuel injectors  132  of engine  112 . While only a single fuel injector  132  is shown, additional injectors may be provided for each cylinder. For example, engine  112  may be a direct injection gasoline engine and additional injectors may be provided for each cylinder. It will be appreciated that fuel system  106  may be a return-less fuel system, a return fuel system, or various other types of fuel system. In some examples, a fuel pump may be configured to draw the tank&#39;s liquid from the tank bottom. Vapors generated in fuel system  106  may be routed to fuel vapor recovery system (evaporative emissions control system)  154 , described further below, via conduit  134 , before being purged to the engine intake  23 . To isolate fuel system  106  from evaporative emissions system  154 , a fuel tank isolation valve (FTIV)  181  may be included in conduit  134 . 
     Fuel vapor recovery system  154  includes a fuel vapor retaining device or fuel vapor storage device, depicted herein as fuel vapor canister  104 . Canister  104  may be filled with an adsorbent capable of binding large quantities of vaporized HCs. In one example, the adsorbent used is activated charcoal. Canister  104  may include a buffer  104   a  (or buffer region) and a non-buffer region  104   b,  each of the buffer  104   a  and the non-buffer region  104   b  comprising the adsorbent. The adsorbent in the buffer  104   a  may be the same as, or different from, the adsorbent in the non-buffer region  104   b.  As illustrated, the volume of buffer  104   a  may be smaller than (e.g. a fraction of) the volume of the non-buffer region  104   b.  Buffer  104   a  may be positioned within canister  104  such that during canister loading, fuel tank vapors are first adsorbed within the buffer, and then when the buffer is saturated, further fuel tank vapors are adsorbed in the non-buffer region  104   b  of canister  104 . In comparison, during canister purging, fuel vapors may first be desorbed from the non-buffer region  104   b  (e.g., to a threshold amount) before being desorbed from the buffer  104   a.  In other words, loading and unloading of the buffer is not linear with the loading and unloading of the non-buffer region. As such, the effect of the canister buffer is to dampen any fuel vapor spikes flowing from the fuel tank to the canister, thereby reducing the possibility of any fuel vapor spikes going to the engine. 
     Canister  104  may receive fuel vapors from fuel tank  128  through conduit  134 . While the depicted example shows a single canister, it will be appreciated that in alternate embodiments, a plurality of such canisters may be connected together. Canister  104  may communicate with the atmosphere through vent line  136 . An evaporative level check monitor (ELCM)  182  may be disposed in vent line  136  and may be configured to control venting and/or assist in detection of undesired evaporative emissions. ELCM  182  may include an ELCM pressure sensor  183 . Details of how ELCM  182  operates will be discussed in further detail below with regard to  FIGS. 3A-4B . 
     In some examples, one or more oxygen sensors (not shown) may be positioned in the engine intake  116 , or coupled to the canister  104  (e.g., downstream of the canister), to provide an estimate of canister load. In still further examples, one or more temperature sensors  157  may be coupled to and/or within canister  104 . For example, as fuel vapor is adsorbed by the adsorbent in the canister, heat is generated (heat of adsorption). Likewise, as fuel vapor is desorbed by the adsorbent in the canister, heat is consumed. In this way, the adsorption and desorption of fuel vapor by the canister may be monitored and estimated based on temperature changes within the canister, and may be used to estimate canister load. 
     FTIV  181  may allow the fuel vapor canister  104  to be maintained at a low pressure or vacuum without increasing the fuel evaporation rate from the tank (which would otherwise occur if the fuel tank pressure were lowered). The fuel tank  128  may hold a plurality of fuel blends, including fuel with a range of alcohol concentrations, such as various gasoline-ethanol blends, including E 10 , E 85 , gasoline, etc., and combinations thereof. 
     Fuel vapor recovery system  154  may include a dual path purge system  171 . Purge system  171  is coupled to canister  104  via a conduit  150 . Conduit  150  may include a canister purge valve (CPV)  158  disposed therein. CPV  158  may regulate the flow of vapors along duct  150 . The quantity and rate of vapors released by CPV  158  may be determined by the duty cycle of an associated CPV solenoid (not shown). In one example, the duty cycle of the CPV solenoid may be determined by controller  166  responsive to engine operating conditions, including, for example, an air-fuel ratio. By commanding CPV  158  to be closed, the controller may seal the fuel vapor canister from the fuel vapor purging system, such that no vapors are purged via the fuel vapor purging system. In contrast, by commanding CPV  158  to be open, the controller may enable the fuel vapor purging system to purge vapors from the fuel vapor canister. 
     Fuel vapor canister  104  operates to store vaporized hydrocarbons (HCs) from fuel system  106 . Under some operating conditions, such as during refueling, fuel vapors present in the fuel tank may be displaced when liquid is added to the tank. The displaced air and/or fuel vapors may be routed from the fuel tank  128  to the fuel vapor canister  104 , and then to the atmosphere through vent line  136 . In this way, vaporized HCs may be stored in fuel vapor canister  104 . During a later engine operation, the stored vapors may be released back into the incoming air charge via fuel vapor purging system  171 . 
     In some examples, an air intake system hydrocarbon trap (AIS HC)  169  may be placed in the intake manifold of engine  112  to adsorb fuel vapors emanating from unburned fuel in the intake manifold, puddled fuel from leaky injectors and/or fuel vapors in crankcase ventilation emissions during engine-off periods. The AIS HC  169  may include a stack of consecutively layered polymeric sheets impregnated with HC vapor adsorption/desorption material. Alternately, the adsorption/desorption material may be filled in the area between the layers of polymeric sheets. The adsorption/desorption material may include one or more of carbon, activated carbon, zeolites, or any other HC adsorbing/desorbing materials. When the engine is operational causing an intake manifold vacuum and a resulting airflow across AIS HC  169 , the trapped vapors may be passively desorbed from the AIS HC and combusted in the engine. Thus, during engine operation, intake fuel vapors are stored and desorbed from AIS HC  169 . In addition, fuel vapors stored during an engine shutdown can also be desorbed from the AIS HC during engine operation. In this way, AIS HC  169  may be continually loaded and purged, and the trap may reduce evaporative emissions from the intake passage even when engine  112  is shut down. 
     Conduit  150  is coupled to an ejector  140  in an ejector system  141  and includes a second check valve (CV2)  170  disposed therein between ejector  140  and CPV  158 . CV2  170  may prevent intake air from flowing through from the ejector into conduit  150 , while allowing flow of air and fuel vapors from conduit  150  into ejector  140 . CV2  170  may be a vacuum-actuated check valve, for example, that opens responsive to vacuum derived from ejector  140 . 
     A conduit  151  couples conduit  150  to intake  23  at a position within conduit  150  between CV2  170  and CPV  158  and at a position in intake  23  downstream of throttle  114 . For example, conduit  151  may be used to direct fuel vapors from canister  104  to intake  23  using vacuum generated in intake manifold  116  during a purge event. Conduit  151  may include a first check valve (CV1)  153  disposed therein. CV1  153  may prevent intake air from flowing through from intake manifold  116  into conduit  150 , while allowing flow of fluid and fuel vapors from conduit  150  into intake manifold  116  via conduit  151  during a canister purging event. CV1  153  may be a vacuum-actuated check valve, for example, that opens responsive to vacuum derived from intake manifold  116 . 
     Conduit  148  may be coupled to ejector  140  at a first port or inlet  142 . Conduit  148  may include a third check valve (CV3)  184 . CV3  184  may open in response to a positive pressure with respect to atmospheric pressure greater than a CV3 opening threshold, the positive pressure in intake conduit  118 . For example, during boost conditions where compressor  126  is activated, CV3  184  may open to direct boosted air to ejector system  141 . Alternatively, as will be elaborated further below, CV3  184  may prevent the flow of positive pressure with respect to atmospheric pressure from flowing the other direction through CV3  184 , specifically from conduit  148  through CV3  184  to intake conduit  118 . Thus, it may be understood that CV3  184  comprises a pressure/vacuum-actuated valve, that opens responsive to boosted air in intake conduit  118  to allow positive pressure with respect to atmospheric pressure to enter into ejector system  141 , but which prevents positive pressure from traversing CV3 in the reverse direction (e.g. to intake conduit  118 ). Accordingly, during boost conditions, conduit  148  may direct compressed air in intake conduit  118  downstream of compressor  126  into ejector  140  via port  142 . 
     Ejector  140  may also be coupled to intake conduit  118  at a position upstream of compressor  126  via a shut-off valve  193 . Shut-off valve  193  is hard-mounted directly to air induction system  173  along conduit  118  at a position between air filter  174  and compressor  126 . For example, shut-off valve  193  may be coupled to an existing AIS nipple or other orifice, e.g., an existing SAE male quick connect port, in AIS  173 . Hard-mounting may include a direct mounting that is inflexible. For example, an inflexible hard mount could be accomplished through a multitude of methods including spin welding, laser bonding, or adhesive. Shut-off valve  193  is configured to close in response to undesired emissions detected downstream of outlet  146  of ejector  140 . As shown in  FIG. 1 , in some examples, a conduit or hose  152  may couple the third port  146  or outlet of ejector  140  to shut-off valve  193 . In this example, if a disconnection of shut-off valve  193  with AIS  173  is detected, then shut-off valve  193  may close so air flow from the engine intake downstream of the compressor through the converging orifice in the ejector is discontinued. However, in other examples, shut-off valve may be integrated with ejector  140  and directly coupled thereto. 
     Ejector  140  includes a housing  168  coupled to ports  146 ,  144 , and  142 . In one example, only the three ports  146 ,  144 , and  142  are included in ejector  140 . Ejector  140  may include various check valves disposed therein. For example, ejector  140  may include a check valve positioned adjacent to each port in ejector  140  so that unidirectional flow of fluid or air is present at each port. For example, air from intake conduit  118  downstream of compressor  126  may be directed into ejector  140  via inlet port  142  and may flow through the ejector and exit the ejector at outlet port  146  before being directed into intake conduit  118  at a position upstream of compressor  126 . This flow of air through the ejector may create a vacuum due to the Venturi effect at inlet port  144  so that vacuum is provided to conduit  150  via port  144  during boosted operating conditions. In particular, a low pressure region is created adjacent to inlet port  144  which may be used to draw purge vapors from the canister into ejector  140 , when CPV  158  is additionally commanded open. 
     Ejector  140  includes a nozzle  191  comprising an orifice which converges in a direction from inlet  142  toward suction inlet  144  so that when air flows through ejector  140  in a direction from port  142  towards port  146 , a vacuum is created at port  144  due to the Venturi effect. This vacuum may be used to assist in fuel vapor purging during certain conditions, e.g., during boosted engine conditions. In one example, ejector  140  is a passive component. That is, ejector  140  is designed to provide vacuum to the fuel vapor purge system via conduit  150  to assist in purging under various conditions, without being actively controlled. Thus, whereas CPV  158 , and throttle  114  may be controlled via controller  166 , for example, ejector  140  may be neither controlled via controller  166  nor subject to any other active control. In another example, the ejector may be actively controlled with a variable geometry to adjust an amount of vacuum provided by the ejector to the fuel vapor recovery system via conduit  150 . 
     During select engine and/or vehicle operating conditions, such as after an emission control device light-off temperature has been attained (e.g., a threshold temperature reached after warming up from ambient temperature) and with the engine running, the controller  166  may command a changeover valve (not shown at  FIG. 1  but see  FIGS. 3A-3D ) associated with ELCM  182  to fluidically couple canister  104  to atmosphere via vent line  136 , and may further adjust the duty cycle of the CPV solenoid (not shown) and control opening of CPV  158 . Pressures within fuel vapor purging system  171  may then draw fresh air through vent line  136 , fuel vapor canister  104 , and CPV  158  such that fuel vapors flow, or in other words, are purged into conduit  150  from canister  104 . 
     During intake manifold vacuum conditions which may be present, as one example, during an engine idle condition, where manifold pressure is below atmospheric pressure by a threshold amount, the vacuum in the intake system  23  may draw fuel vapor from the canister through conduits  150  and  151  into intake manifold  116 . In such an example, vacuum may be prevented from being drawn on ejector system via CV2  170  and CV3  184 . 
     The operation of ejector  140  within fuel vapor purging system  171  during boost conditions will next be described. The boost conditions may include conditions during which the mechanical compressor (e.g.  126 ) is in operation. For example, the boost conditions may include one or more of a high engine load condition and a super-atmospheric intake condition, with intake manifold pressure greater than atmospheric pressure by a threshold amount. 
     Fresh air enters intake passage  118  at air filter  174 . During boost conditions, compressor  126  pressurizes the air in intake passage  118 , such that intake manifold pressure is positive with respect to atmospheric pressure. Pressure in intake passage  118  upstream of compressor  126  is lower than intake manifold pressure during operation of compressor  126 , and this pressure differential induces a flow of fluid from intake conduit  118  through duct  148  and into ejector  140  via ejector inlet  142 . This fluid may include a mixture of air and fuel, in some examples. After the fluid flows into the ejector via the port  142 , it flows through the converging orifice  192  in nozzle  191  in a direction from port  142  towards outlet  146 . Because the diameter of the nozzle gradually decreases in a direction of this flow, a low pressure zone is created in a region of orifice  192  adjacent to suction inlet  144 . The pressure in this low pressure zone may be lower than a pressure in duct  150 . When present, this pressure differential provides a vacuum to conduit  150  to draw fuel vapor from canister  104 . This pressure differential may induce flow of fuel vapors from the fuel vapor canister, through CPV  158  (where the CPV is commanded open), and into port  144  of ejector  140 . Upon entering the ejector, the fuel vapors may be drawn along with the fluid from the intake manifold out of the ejector via outlet port  146  and into intake  118  at a position upstream of compressor  126 . Operation of compressor  126  then draws the fluid and fuel vapors from ejector  140  into intake passage  118  and through the compressor  126 . After being compressed by compressor  126 , the fluid and fuel vapors flow through charge air cooler  156 , for delivery to intake manifold  116  via throttle  114  It may be understood that the above-described operation of ejector  140  during boost conditions relates to an engine-on condition, where the vehicle is in operation and the engine is combusting air and fuel. However, there may be other opportunities for providing pressurized air to ejector system  141 , with the engine off. Such examples will be described in detail below. 
     Vehicle system  100  may further include a control system  160 . Control system  160  is shown receiving information from a plurality of sensors  162  (various examples of which are described herein) and sending control signals to a plurality of actuators  164  (various examples of which are described herein). As one example, sensors  162  may include an exhaust gas sensor  125  (located in exhaust manifold  120 ) and various temperature and/or pressure sensors arranged in intake system  23 . For example, a pressure or airflow sensor  115  in intake conduit  118  downstream of throttle  114 , a pressure or air flow sensor  117  in intake conduit  118  between compressor  126  and throttle  114 , and/or a pressure or air flow sensor  119  in intake conduit  118  upstream of compressor  126 . In some examples, pressure sensor  119  may comprise a dedicated barometric pressure sensor. Other sensors such as additional pressure, temperature, air/fuel ratio, and composition sensors may be coupled to various locations in the vehicle system  100 . As another example, actuators  164  may include fuel injectors  132 , throttle  114 , compressor  126 , a fuel pump of pump system  130 , etc. The control system  160  may include an electronic controller  166 . The controller may receive input data from the various sensors, process the input data, and trigger the actuators in response to the processed input data based on instruction or code programmed therein corresponding to one or more routines. 
     In some examples, the controller may be placed in a reduced power mode or sleep mode, wherein the controller maintains essential functions only, and operates with lower battery consumption than in a corresponding awake mode. For example, the controller may be placed in a sleep mode following a vehicle-off event in order to perform a diagnostic routine at a duration following the vehicle-off event. The controller may have a wake input that allows the controller to be returned to an awake mode based on an input received from one or more sensors. In some examples, the controller may schedule a wake-up time, which may comprise setting a timer and when the timer elapses, the controller may be woken up from sleep mode. 
     Diagnostic tests may be periodically performed on the evaporative emissions control system  154  and fuel system  106  in order to indicate the presence or absence of undesired evaporative emissions and/or to diagnose functionality of one or more of check valves (e.g. CV1, CV2, CV3) CPV, ejector system, etc. As one example, under natural aspiration conditions (e.g. intake manifold vacuum conditions) where the engine  112  is being operated to combust air and fuel, the ELCM changeover valve (discussed in further detail at  FIGS. 3A-3D ) may be commanded such that vent line  136  is sealed from atmosphere, and CPV  158  may be commanded open. FTIV  181  may additionally be commanded open, such that pressure in the evaporative emissions system and fuel system may be monitored via fuel tank pressure transducer (FTPT)  107 . However, in other examples FTIV  181  may be maintained closed, where pressure in the evaporative emissions system may be monitored via pressure sensor  183  associated with ELCM  182 . In this way, during natural aspiration conditions where the engine is in operation, the evaporative emissions control system  154  (and in examples where FTIV  181  is also commanded open, fuel system  106 ) may be evacuated. If a threshold vacuum (e.g. negative pressure threshold with respect to atmospheric pressure) is reached during evacuating the evaporative emissions control system  154  (and fuel system  106  in a case where FTIV  181  is commanded open), an absence of gross (e.g. a source of undesired evaporative emissions greater than  0 . 09 ″) undesired evaporative emissions may be indicated. Furthermore, if the threshold vacuum is reached, then it may be indicated that the first check valve (CV1)  153  is not stuck closed or substantially closed, and that CPV  158  opened as commanded. Responsive to the threshold vacuum being reached, CPV  158  may be commanded closed and pressure in evaporative emissions system (and in some examples fuel system as well) may be monitored. A pressure rise (e.g. bleed-up) greater than a predetermined pressure rise threshold, or a pressure rise rate (e.g. bleed-up rate) rate greater than a predetermined pressure rise rate threshold may indicate the presence of non-gross (e.g. 0.02″, or 0.04″) undesired evaporative emissions. 
     Another example describes a diagnostic test for the presence or absence of undesired evaporative emissions stemming from the fuel system and/or evaporative emissions system, under boost conditions, where the engine is operating to combust air and fuel. Similar to that discussed above, in such an example the changeover valve associated with ELCM  182  may be commanded to seal vent line  136  from atmosphere, and CPV  158  may be commanded open. In some examples, FTIV  181  may additionally be commanded open, whereas in other examples FTIV  181  may be commanded or maintained closed. In this way, during boost conditions where the engine is operating to combust air and fuel, the evaporative emissions control system  154  (and in some examples fuel system  106  as well) may be evacuated via vacuum stemming from ejector system  141  as discussed above, in order to ascertain the presence or absence of undesired evaporative emissions. 
     In such an example, one or more of FTPT  107  and/or ELCM pressure sensor  183 , depending on whether or not FTIV  181  was commanded open, may be used to monitor pressure in the fuel system and/or evaporative emissions system. If the threshold vacuum (e.g. negative pressure threshold with respect to atmospheric pressure) is reached during evacuating the fuel system and/or evaporative emissions control system, an absence of gross undesired evaporative emissions may be indicated. Responsive to the threshold vacuum being reached, CPV  158  may be commanded closed, and pressure bleedup monitored as discussed above to ascertain presence or absence of non-gross undesired evaporative emissions. 
     Furthermore, in such an example, if the threshold vacuum is reached under boosted engine operation, then it may be indicated that the second check valve (CV2)  170  is not stuck closed or substantially closed, and that the ejector system is functioning as desired or expected. 
     However, conducting such a diagnostic under boost conditions may not always be feasible for particular drive cycles, as certain drive cycles may not include boost conditions of sufficient duration to conduct such a diagnostic. As one example, in a case where it is desired to use boosted engine operation to evacuate the evaporative emissions system and the fuel system, depending on fuel tank size and fuel level, it may take as much as 15-20 seconds to evacuate the evaporative emissions system and fuel system to the threshold vacuum. However, boost duration may be as low as 1-3 seconds, thus preventing the ability to conduct the diagnostic. 
     To address such an issue, an engine-off boost conduit, referred to herein as EOBC  185  may be included in vehicle system  100 , along with routing valve (RV)  186 . RV  186  may be under control of controller  166 , and may include a solenoid actuator  187 . When solenoid actuator  187  is off, in other words when current is not supplied to solenoid actuator  187  under control of controller  166 , it may be understood that RV  186  is in a first RV position, as depicted at  FIG. 1 . When RV  186  is configured in the first RV position, as depicted at  FIG. 1 , canister  104  may be fluidically coupled to ELCM  182  along vent line  136 . Furthermore, EOBC  185  may be sealed from atmosphere when RV  186  is configured in the first RV position as depicted at  FIG. 1 . Alternatively, turning to  FIG. 2 , the same vehicle system  100  is depicted, with RV  186  configured in a second RV position. Specifically, it may be understood that when solenoid actuator  187  is commanded on, or in other words when controller  166  commands current to be supplied to solenoid actuator  187 , RV  186  may adopt the second RV position as depicted at  FIG. 2 . When RV  186  is commanded to the second RV position, EOBC  185  may be fluidically coupled to ELCM  182  along vent line  136 , whereas canister  104  may be sealed from atmosphere along vent line  136  as depicted at  FIG. 2 . 
     In this way, depending on the position of RV  186 , ELCM  182  may be selectively fluidically coupled to canister  104 , or to EOBC  185 . Accordingly, this may in turn allow for relying on ELCM  182  to, when RV  186  is commanded to the first RV position as depicted at  FIG. 1 , evacuate the fuel system and/or evaporative emissions system to conduct certain diagnostics, and to alternatively conduct other diagnostics when RV  186  is commanded to the second RV position as depicted at  FIG. 2 . 
     Specifically, as will be elaborated further below, diagnostics for presence or absence of undesired evaporative emissions stemming from the evaporative emissions system and/or fuel system may be conducted via evacuating the fuel system and/or evaporative emissions system via ELCM  182  with CPV  158  commanded closed and RV  186  commanded to the first RV position as depicted at  FIG. 1 . Responsive to a threshold vacuum being reached, an absence of gross undesired evaporative emissions may be indicated, ELCM  182  may be commanded off, and the ELCM changeover valve (not shown at  FIG. 1  but refer to  FIGS. 3A-3D ) may be controlled to seal vent line  136  from atmosphere. Then, similar to that discussed above pressure bleedup may be monitored in the sealed fuel system and/or evaporative emissions system to indicate presence or absence of non-gross undesired evaporative emissions. 
     Alternatively, with RV  186  commanded to the second RV position as depicted at  FIG. 2 , ELCM  182  may be used to direct pressurized air into EOBC  185  and into conduit  148 . Thus, it may be understood that EOBC  185  may be coupled to conduit  148 . In some examples, EOBC valve  189  may be included in EOBC  185 , and may include a solenoid actuator (not shown) which may allow for controller  166  to command EOBC valve  189  to an open or closed position. Alternatively, in another example EOBC valve  189  may comprise a pressure/vacuum-actuated check valve, which may open responsive to pressurized air being communicated through EOBC  185  via ELCM  182  operating in a pressure-mode to supply pressurized air to ejector system  141  via EOBC  185 , but which may close responsive to pressurized air being introduced into conduit  148  from intake passage  118 . 
     Accordingly, it may be understood that, with RV  186  commanded to the second RV position as depicted at  FIG. 2 , pressurized air may be supplied to ejector system  141  via ELCM  182  operating in the pressure mode. In this way, an engine-off boost test diagnostic may be conducted, that does not rely on engine operation in order to introduce positive pressure to ejector system  141 . Because, as discussed above, boost conditions that are derived from engine operation may not be sufficient for conducting diagnostics that rely on positive pressure being introduced to ejector system  141  due to infrequent and/or short engine-on boost duration, providing vehicle system  100  with an alternative means (ability to introduce positive pressure to ejector system  141  via operating ELCM  182  in pressure-mode) may improve ability to conduct diagnostics that rely on positive pressure being introduced to ejector system  141 . Specifically, as will be elaborated below, in a situation where it is determined via the controller that the evaporative emissions system is free from the presence of undesired evaporative emissions and that the CPV is functioning as desired, pressure introduced to ejector system  141  via the ELCM operating in pressure-mode may be used to ascertain whether one or more of the ejector and/or CV2  170  are functioning as desired or expected, or are degraded to some extent. 
     As discussed above, ELCM  182  may include a changeover valve (COV). Accordingly, turning to  FIGS. 3A-3D , they schematically depict examples of ELCM  182  control, including control over the COV, in various conditions in accordance with the present disclosure. As discussed with regard to  FIGS. 1-2 , when RV  186  is commanded to the first RV position, ELCM  182  may be fluidically coupled to canister  104 . Alternatively, when RV  186  is commanded to the second RV position, ELCM  182  may be fluidically coupled to EOBC  185 . For simplicity with regard to  FIGS. 3A-3D , operation of ELCM will be discussed in terms of ELCM  182  being fluidically coupled to the canister  104  as opposed to the EOBC  185 . However, it may be understood that ELCM  182  may be controlled in similar fashion as that discussed below, under circumstances where ELCM  182  is fluidically coupled to EOBC  185 . 
     Turning to  FIGS. 3A-3D , ELCM  182  includes changeover valve (COV)  315 , a pump  330 , and pressure sensor  183 . Pump  330  may be a reversible pump, for example, a vane pump. COV  315  may be movable between a first COV position a second COV position. In the first COV position, as shown in  FIGS. 3A and 3C , air may flow through ELCM  182  via first flow path  320 . In the second COV position, as shown in  FIGS. 3B and 3D , air may flow through ELCM  182  via second flow path  325 . The position of COV  315  may be controlled by solenoid  310  via compression spring  305 . ELCM  182  may also comprise reference orifice  340 . Reference orifice  340  may have a diameter corresponding to the size of a threshold for non-gross undesired evaporative emissions to be tested, for example,  0 . 02 ″. In either the first or second COV position, pressure sensor  183  may generate a pressure signal reflecting the pressure within ELCM  182 . Operation of pump  330  and solenoid  310  may be controlled via signals received from controller  166 . 
     As shown in  FIG. 3A , COV  315  is in the first COV position, and pump  330  is activated in a first direction, otherwise referred to as a vacuum-mode of operation. Air flow through ELCM  182  in this configuration is represented by arrows. In this configuration, pump  330  may draw a vacuum on reference orifice  340 , and pressure sensor  183  may record the vacuum level within ELCM  182 . This reference check vacuum level reading may then become the threshold for the presence or absence of undesired evaporative emissions in a subsequent evaporative emissions test diagnostic. 
     As shown in  FIG. 3B , COV  315  is in the second COV position, and pump  330  is activated in the first direction. This configuration allows pump  330  to draw a vacuum on the fuel system and/or evaporative emissions system. Air flow through ELCM  182  in this configuration is represented by arrows. As discussed above,  FIG. 3B  relates to a situation where RV  186  is commanded to the first RV position. If instead RV  186  were commanded to the second RV position, then rather than drawing a vacuum on the fuel system and/or evaporative emissions system, the vacuum may be applied on the EOBC  185 . 
     As shown in  FIG. 3C , COV  315  is in the first COV position, and pump  330  is de-activated. This configuration allows for air to freely flow between atmosphere and the canister. This configuration may be used during a canister purging operation, for example, and may additionally be used during vehicle operation when a purging operation is not being conducted, and when the vehicle is not in operation. 
     As shown in  FIG. 3D , COV  315  is in the second COV position, and pump  330  is activated in a second direction, otherwise referred to as a pressure-mode of operation, the second direction opposite from the first direction. In this configuration, pump  330  may pull air from atmosphere into the fuel system and/or evaporative emission system. As discussed above,  FIG. 3D  relates to a situation where RV  186  is commanded to the first RV position. If instead RV  186  were commanded to the second RV position, then rather than applying a positive pressure on the fuel system and/or evaporative emissions system, the positive pressure would be directed through EOBC  185 . 
     As depicted at  FIG. 3C , with pump  330  off and COV  315  configured in the first COV position, air flows freely between the canister and atmosphere when RV  186  is configured in the first RV position. Similarly, if RV  186  were configured in the second RV position, the air would flow freely between atmosphere and EOBC  185 . While not explicitly illustrated, it may be understood that to simply seal either the canister from atmosphere (when RV  186  is commanded to the first RV position), or to seal the EOBC from atmosphere (when RV  186  is commanded to the second RV position), COV  315  may be configured in the second COV position, with pump  330  off. 
     As discussed, pump  330  may be operated in the pressure-mode or the vacuum-mode. Accordingly, turning to  FIGS. 4A-4B , they depict an example circuit  400  that may be used for reversing a pump motor of ELCM  182 . Circuit  400  schematically depicts an H-Bridge circuit that may be used to run a motor  410  in a first (forward) direction (e.g. vacuum-mode) and alternately in a second (reverse) direction (e.g. pressure-mode). Circuit  400  comprises a first (LO) side  420  and a second (HI) side  430 . Side  420  includes transistors  421  and  422 , while side  430  includes transistors  431  and  432 . Circuit  400  further includes a power source  440 . 
     In  FIG. 4A , transistors  421  and  432  are activated, while transistors  422  and  431  are off. In this confirmation, the left lead  451  of motor  410  is connected to power source  440 , and the right lead  452  of motor  410  is connected to ground. In this way, motor  400  may run in a forward direction. 
     In  FIG. 4B , transistors  422  and  431  are activated, while transistors  421  and  432  are off. In this confirmation, the right lead  452  of motor  410  is connected to power source  440 , and the left lead  451  of motor  410  is connected to ground. In this way, motor  400  may run in a reverse direction. 
     Accordingly, discussed herein a system for a vehicle may comprise a pump that is selectively fluidically coupled to a vent line upstream of a fuel vapor storage canister positioned in an evaporative emissions system when a routing valve is commanded to a first routing valve position, and that is alternatively selectively fluidically coupled to an ejector system when the routing valve is commanded to a second routing valve position. Such a system may further comprise a a controller with computer readable instructions stored on non-transitory memory that when executed during an engine-off condition, cause the controller to command the routing valve to the second position, activate the pump to route a positive pressure to the ejector system, monitor a vacuum generated via the ejector system responsive to routing the positive pressure to the ejector system, and indicate that the ejector system is degraded responsive to the vacuum failing to reach or exceed a vacuum build threshold. 
     Such a system may further comprise a fuel system selectively fluidically coupled to the evaporative emissions system via a fuel tank isolation valve, the fuel system including a fuel tank pressure transducer. The controller may store further instructions to command open the fuel tank isolation valve and monitor the vacuum generated via the ejector system via the fuel tank pressure transducer. 
     For such a system, the pump may be fluidically coupled to the ejector system when the routing valve is commanded to the second routing valve position by way of an engine-off boost conduit, the engine-off boost conduit further including an engine-off boost conduit valve. In such an example, the controller may store further instructions to command open the engine-off boost conduit valve in order to route the positive pressure to the ejector system. 
     Such a system may further comprise a conduit positioned upstream of the ejector system that receives the positive pressure that is routed to the ejector system. The conduit may further include a passive check valve that prevents the positive pressure from being routed to an intake conduit of an engine of the vehicle. 
     Such a system may further comprise a canister purge valve positioned in a purge conduit that couples the fuel vapor storage canister to an engine intake and to the ejector system. In such an example, the controller may store further instructions to command open the canister purge valve when routing the positive pressure to the ejector system. 
     As discussed above, it may be desirable to rely on ELCM  182  to introduce positive pressure into ejector system  141  during engine-off conditions, as there may be limited and/or insufficient times for doing so during engine-on operation. The introduction of such positive pressure to the ejector system may be used to diagnose whether the ejector (e.g.  140 ) and/or CV2 (e.g.  170 ) are degraded, or are functioning as desired. However, in order to accurately assess presence or absence of degradation of the ejector and/or CV2, certain conditions may first have to be met. 
     One such condition includes an indication that the EOBC (e.g.  185 ) is not degraded, and that the EOBC valve (e.g.  189 ) is not stuck closed. Accordingly, turning to  FIG. 5 , an example method  500  is depicted, detailing methodology for determining whether the EOBC is degraded and whether the EOBC valve is stuck closed or not. Method  500  will be described with reference to the systems described herein and shown in  FIGS. 1-4B , though it will be appreciated that similar methods may be applied to other systems without departing from the scope of this disclosure. Instructions for carrying out method  500  and the rest of the methods included herein may be executed by a controller, such as controller  166  of  FIG. 1 , based on instructions stored in non-transitory memory, and in conjunction with signals received from sensors of the engine system, such as temperature sensors, pressure sensors, and other sensors described in  FIGS. 1-3D . The controller may employ actuators such as RV (e.g.  186 ), ELCM pump (e.g.  330 ), COV (e.g.  315 ), EOBC valve (e.g.  189 ), CPV (e.g.  158 ), FTIV (e.g.  181 ), etc., to alter states of devices in the physical world according to the methods depicted below. 
     Method  500  begins at  503  and may include estimating and/or measuring vehicle operating conditions. Operating conditions may be estimated, measured, and/or inferred, and may include one or more vehicle conditions, such as vehicle speed, vehicle location, etc., various engine conditions, such as engine status, engine load, engine speed, A/F ratio, manifold air pressure, etc., various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc., various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc., as well as various ambient conditions, such as ambient temperature, humidity, barometric pressure, etc. 
     Proceeding to  506 , method  500  includes indicating whether conditions are met for conducting the EOBC diagnostic. In one example, conditions being met may include an indication that the engine is not combusting air and fuel. However, in other examples, conditions being met may include an indication that the engine is operating to combust air and fuel, provided that the engine is not operating in boost mode (in other words, provided there is not a positive pressure with respect to atmospheric pressure present in the intake passage (e.g.  118 ). For example, an engine idle condition where intake manifold vacuum is present, may comprise a circumstance where conditions are indicated to be met. Conditions being met at  506  may additionally or alternatively include an indication that a predetermined amount of time (e.g. 5 days, 3 days, 2 days, 1 day, etc.) has elapsed since a prior EOBC diagnostic was conducted. Conditions being met at  506  may additionally or alternatively include an indication that there is not already degradation indicated for the EOBC (e.g.  185 ) and/or the EOBC valve (e.g.  189 ). Conditions being met at  506  may additionally or alternatively include an indication that the ELCM is not being utilized for another diagnostic purpose. Conditions being met at  506  may additionally or alternatively include an indication that a canister purging operation is not in progress. In some examples, conditions being met may include a key-off event, or may include an indication that the controller has been woken up from a sleep state to conduct the diagnostic. 
     If, at  506 , conditions are not indicated to be met for conducting the EOBC diagnostic, method  500  may proceed to  509 . At  509 , method  500  may include maintaining current vehicle operating status. For example, the RV (e.g.  186 ) may be maintained in its current configuration, the ELCM (e.g.  182 ) may be maintained in its current state of operation, the EOBC valve (e.g.  189 ) may be maintained in its current state of operation, etc. Method  500  may then end. 
     Returning to  506 , in response to conditions being met for conducting the EOBC diagnostic, method  500  may proceed to  512 . At  512 , method  500  may include commanding the RV to the second RV position. Proceeding to  515 , method  500  may include commanding or maintaining the ELCM COV (e.g.  315 ) in the first position. Proceeding to  518 , method  500  may include activating the ELCM pump in the forward mode, also referred to herein as the vacuum-mode of operation, to draw air flow across the reference orifice (e.g.  340 ), as depicted at  FIG. 3A . The ELCM pump may be operated in vacuum-mode for a predetermined duration, and/or until a steady-state pressure as monitored via the ELCM pressure sensor (e.g.  183 ) is indicated. The steady-state pressure or reference pressure may comprise a threshold pressure that may subsequently be used for conducting the EOBC diagnostic. 
     Accordingly, with the reference pressure obtained at  521 , method  500  may proceed to  524 . At  524 , method  500  may include commanding the ELCM COV to the second position, and commanding or maintaining closed the EOBC valve. Continuing at  527 , method  500  may include activating the ELCM pump in the vacuum-mode, to draw a vacuum on the EOBC. Once the ELCM pump is activated to draw the negative pressure with respect to atmospheric pressure on the EOBC, method  500  may proceed to  530 . At  530 , method  500  may include monitoring the vacuum build via the ELCM pressure sensor. While not explicitly illustrated, monitoring the vacuum build may include monitoring the vacuum build for a predetermined duration, the predetermined duration comprise an amount of time where, if there is an absence of degradation of the EOBC, then it may be expected that the vacuum would build to the reference pressure obtained at step  521 . 
     Accordingly, at  533 , method  500  may include indicating whether the vacuum build has reached or exceed the reference pressure. If so, then method  500  may proceed to  536 , where an absence of degradation of the EOBC may be indicated. Furthermore, it may be indicated that the EOBC valve is not degraded, at least in terms of sealing the EBOC line. Such results may be stored at the controller. 
     Proceeding to  539 , method  500  may include deactivating the ELCM pump. However, while not explicitly illustrated, it may be understood that the ELCM COV may be maintained in the second COV position. In this way, the vacuum in the EOBC may be trapped due to the ELCM COV being in the second COV position and the EOBC valve being closed. 
     Continuing to  542 , method  500  may include commanding open the EOBC valve. It may be understood that commanding the EOBC valve open may relieve the pressure trapped in the EOBC, provided that the EOBC valve opens when commanded to do so via the controller. Accordingly, at  545 , method  500  may include indicating whether the vacuum is relieved, or in other words, if the EOBC pressure returns to atmospheric pressure (or within a predetermined threshold such as less a 5% difference or less from atmospheric pressure) upon the commanding open of the EOBC valve. If so, then method  500  may proceed to  548 , where it may be indicated that the EOBC valve is not stuck closed. In other words, because commanding open the EOBC valve resulted in the pressure in the EOBC being relieved, then the EOBC valve must have opened. Such a result may be stored at the controller. Continuing at  551 , method  500  may include commanding closed the EOBC valve. 
     Returning to  545 , if pressure decay is not indicated, or in other words, if the pressure decay has not resulted in pressure in the EOBC line being relieved to within the predetermined threshold of atmospheric pressure, then method  500  may proceed to  554 . At  554 , method  500  may include indicating the EOBC valve is stuck closed. Such a result may be stored at the controller. Continuing at  551 , method  500  may include commanding closed the EOBC valve. 
     Returning to  533 , under circumstances where the vacuum build did not reach or exceed the reference pressure, then method  500  may proceed to  557  where a presence of degradation of the EOBC may be indicated. In other words, because the ELCM pump was unable to pull draw down pressure in the EOBC to the reference pressure, either the EOBC includes a source of degradation greater than the size of the reference orifice associated with the ELCM, or the EOBC valve is stuck open. Such a result may be stored at the controller. Proceeding to  560 , method  500  may include deactivating the ELCM pump. 
     Whether EOBC degradation is indicated (step  557 ), a stuck closed EOBC valve is indicated (step  554 ) or that the EOBC valve is not stuck closed is indicated (step  548 ), at  563 , method  500  may include commanding the ELCM COV to the first position. In doing so, if there is any pressure that remains trapped in the EOBC, then the pressure may be relieved via the ELCM COV being in the first position (refer to  FIG. 3C ). Proceeding to  567 , method  500  may include commanding the RV to the first RV position. Continuing at  570 , method  500  may include updating vehicle operating conditions. Specifically, if there is EOBC degradation or if the EOBC valve is stuck closed, then updating vehicle operating conditions may include preventing the conducting of the diagnostic to assess ejector system functionality (see  FIG. 9 ) that relies on the ELCM pump introducing positive pressure with respect to atmospheric pressure into the ejector system via the EOBC. Furthermore, in response to an indication of EOBC degradation or that the EOBC valve is stuck closed, a malfunction indicator light (MIL) may be illuminated at the vehicle dash, alerting the vehicle operator of a request to service the vehicle to mitigate the issue. Method  500  may then end. 
     As discussed, another condition which may adversely impact the diagnostic for assessing ejector system functionality by introducing positive pressure to the ejector system via the EOBC may include a stuck open CV3 (e.g.  184 ). Specifically, a stuck open CV3 may result in insufficient positive pressure being introduced to the ejector system for conducting the ejector system diagnostic as per  FIG. 9 . Accordingly, turning to  FIG. 6 , an example method  600  is depicted, detailing a diagnostic routine for determining whether the CV3 (e.g.  184 ) is stuck open. Specifically, method  600  includes commanding the RV to the second position, and commanding the EOBC valve open, then directing a positive pressure with respect to atmospheric pressure to the ejector system via the ELCM operating in the pressure-mode, and monitoring pressure in an intake of the engine downstream of the charge air cooler. A pressure change greater than a predetermined pressure change threshold in the intake passage (e.g.  118 ) may indicate that the CV3 is stuck open. If the CV3 were not stuck open, then an absence of pressure change would be expected in the intake passage. 
     As discussed, instructions for carrying out method  600  may be executed by a controller, such as controller  166  of  FIG. 1 , based on instructions stored in non-transitory memory, and in conjunction with signals received from sensors of the engine system, such as temperature sensors, pressure sensors, and other sensors described in  FIGS. 1-3D . The controller may employ actuators such as RV (e.g.  186 ), ELCM pump (e.g.  330 ), COV (e.g.  315 ), EOBC valve (e.g.  189 ), CPV (e.g.  158 ), FTIV (e.g.  181 ), etc., to alter states of devices in the physical world according to the method depicted below. 
     Method  600  begins at  605  and may include estimating and/or measuring vehicle operating conditions. Operating conditions may be estimated, measured, and/or inferred, and may include one or more vehicle conditions, such as vehicle speed, vehicle location, etc., various engine conditions, such as engine status, engine load, engine speed, A/F ratio, manifold air pressure, etc., various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc., various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc., as well as various ambient conditions, such as ambient temperature, humidity, barometric pressure, etc. 
     Continuing to  610 , method  600  may include indicating whether conditions are met for conducting the CV3 diagnostic. Conditions being met at  610  may include an indication that the EOBC is free from degradation, and that the EOBC valve is not stuck closed (see methodology of  FIG. 5 ). Conditions being met at  610  may additionally or alternatively include an indication that the engine is not combusting air and fuel. For example, conditions being met may include a key-off event where the controller is kept awake to conduct the diagnostic, or a situation where the controller is awoken from a sleep state at a particular time during a key-off condition, to conduct the diagnostic. In some examples, conditions being met at  610  may include a condition such as a start/stop event where the engine is pulled down at a stop (e.g. stoplight, in response to traffic conditions, etc.). Conditions being met at  610  may additionally or alternatively include an indication that pressure in the intake passage (e.g.  118 ) is within a threshold (e.g. within 5% or less) of atmospheric pressure, as monitored via, for example, a pressure sensor (e.g.  117 ) positioned therein. Conditions being met at  610  may additionally or alternatively include an indication that a predetermined amount of time (e.g. 5 days, 3 days, 2 days, 1 day, etc.) has elapsed since a prior CV3 diagnostic. 
     If, at  610 , conditions are not indicated to be met for conducting the CV3 diagnostic, method  600  may proceed to  615 . At  615 , method  600  may include maintaining current vehicle operating status. For example, the RV may be maintained in its current status, the ELCM pump may be maintained in its current operational state, the ELCM COV may be maintained in its current operational position, the EOBC valve may be maintained in its current state, the engine may be maintained in its current operational state, etc. Method  600  may then end. 
     Returning to  610 , in response to conditions being indicated to be met for conducting the CV3 diagnostic, method  600  may proceed to  620 . At  620 , method  600  may include commanding the RV to the second RV position. While not explicitly illustrated, it may be understood that the CPV may be commanded or maintained closed. Proceeding to  625 , method  600  may include commanding the EOBC valve open, and commanding the ELCM COV to the second position. Continuing at  630 , method  600  may include activating the ELCM pump in the reverse mode of operation, also referred to herein as the pressure-mode of operation (refer to  FIG. 3D  for a relevant illustration of the ELCM COV in the second position and the ELCM pump activated in the pressure mode). In this way, a positive pressure may be introduced into the EOBC and then to the conduit (e.g.  148 ) that leads to the ejector system. 
     With the ELCM pump configured in the pressure-mode with the RV in the second RV position and the EOBC valve commanded open, method  600  may proceed to  635 . At  635 , method  600  may include monitoring pressure in the intake conduit (e.g.  118 ) downstream of the charge air cooler (e.g.  156 ) via a pressure sensor (e.g.  117 ) positioned in the intake conduit. Monitoring the pressure may include monitoring the pressure for a predetermined duration (e.g. 1 minute, 2 minutes, 3 minutes, etc.). Continuing at  640 , method  600  may include indicating whether a pressure change in the intake conduit is greater than an intake conduit pressure change threshold. The intake conduit pressure change threshold may comprise a positive (with respect to atmospheric pressure) non-zero pressure threshold. The intake conduit pressure change threshold may comprise 5 InH 2 O, 8 InH 2 O, etc. 
     If, at  640 , the pressure change in the intake conduit is not greater than the intake conduit pressure change threshold, then method  600  may proceed to  645 . At  645 , method  600  may include indicating that the CV3 is not stuck open. Alternatively, if at  640 , the pressure change in the intake conduit is greater than the intake conduit pressure change threshold, then method  600  may proceed to  650 , where it may be indicated that the CV3 is stuck open. Whether the CV3 is indicated to be stuck open (step  650 ) or not (step  645 ), method  600  may store the result at the controller. Method  600  may then proceed to  655 , where the controller may deactivate the ELCM pump. 
     With the ELCM pump deactivated at  655 , method  600  may proceed to  660 . At  660 , method  600  may include commanding the RV to the first position, commanding the ELCM COV to the first position, and commanding the EOBC valve closed. Continuing at  665 , method  600  may include updating vehicle operating conditions. Specifically, a MIL may be illuminated at the vehicle dash responsive to an indication that the CV3 is stuck open, alerting the vehicle operator of a request to service the vehicle. Furthermore, in a case where the CV3 is indicated to be stuck open, the diagnostic for determining whether the ejector system is functioning as desired which relies on introducing positive pressure to the ejector system via ELCM pump operation (refer to  FIG. 9 ), may be prevented as any results of the diagnostic may be challenging to interpret due to the stuck open CV3. Method  600  may then end. 
     As will be discussed in further detail below with regard to  FIG. 9  (and also  FIG. 10 ) diagnosing the ejector system via the introduction of positive pressure to the EOBC line and then to the ejector system, may include commanding open the CPV and the FTIV, and relying on pressure change as monitored via the FTPT (e.g.  107 ) to indicate whether the ejector system is degraded or not. Accordingly, other conditions which must be met prior to conducting the ejector system diagnostic may include an indication that the CPV is not stuck closed, that the FTIV is not stuck closed and that there is an absence of a source of undesired evaporative emissions stemming from the fuel system and evaporative emissions system. 
     Accordingly, a diagnostic to assess such parameters is depicted at  FIG. 7 . Specifically,  FIG. 7  depicts a method for assessing presence or absence of a source of undesired evaporative emissions stemming from the fuel system and/or evaporative emissions system, and whether the CPV and/or FTIV is stuck closed. The methodology depicted at  FIG. 7  relies on engine intake manifold vacuum for conducting the diagnostic, while the engine is operating to combust air and fuel. 
     As discussed, instructions for carrying out method  700  may be executed by a controller, such as controller  166  of  FIG. 1 , based on instructions stored in non-transitory memory, and in conjunction with signals received from sensors of the engine system, such as temperature sensors, pressure sensors, and other sensors described in  FIGS. 1-3D . The controller may employ actuators such as RV (e.g.  186 ), ELCM pump (e.g.  330 ), COV (e.g.  315 ), EOBC valve (e.g.  189 ), CPV (e.g.  158 ), FTIV (e.g.  181 ), etc., to alter states of devices in the physical world according to the method depicted below. 
     Method  700  begins at  705  and may include estimating and/or measuring vehicle operating conditions. Operating conditions may be estimated, measured, and/or inferred, and may include one or more vehicle conditions, such as vehicle speed, vehicle location, etc., various engine conditions, such as engine status, engine load, engine speed, A/F ratio, manifold air pressure, etc., various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc., various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc., as well as various ambient conditions, such as ambient temperature, humidity, barometric pressure, etc. 
     Continuing to  710 , method  700  may include indicating whether conditions are met for conducting the natural aspiration evaporative emissions test diagnostic (also referred to herein as natural aspiration evap test). Conditions being met at  710  may include an intake manifold vacuum greater than a predetermined intake manifold vacuum threshold. The intake manifold vacuum threshold may comprise a non-zero, negative pressure threshold with respect to atmospheric pressure. Conditions met at  710  may additionally or alternatively include an indication that a predetermined duration of time (e.g. 5 days, 3 days, 2 days, 1 day, etc.) has elapsed since a prior natural aspiration evap test was conducted. Conditions being met at  710  may additionally or alternatively include an indication that a canister purging event is not in progress. Conditions being met at  710  may additionally or alternatively include an indication that no prior degradation of the CPV, FTIV fuel system and evaporative emissions system is indicated. Conditions being met at  710  may additionally or alternatively include an indication that the engine is operating to combust air and fuel, and that the vehicle is stopped (e.g. at a stoplight). 
     If, at  710 , it is indicated that conditions are not met for conducting the diagnostic, method  700  may proceed to  715 . At  715 , method  700  may include maintaining current vehicle operating conditions. Specifically, the engine may be maintained in its current state of operation, the CPV and FTIV may be maintained in their current operational states, the RV may be maintained in its current state, the ELCM pump and COV may be maintained in their current states, etc. Method  700  may then end. 
     Alternatively, responsive to conditions being met for conducting the natural aspiration evap test at step  710 , method  700  may proceed to  720 . At  720 , method  700  may include commanding the RV to the first RV position, and may further include commanding the ELCM COV to the second COV position. In this way, the canister may be fluidically coupled to the ELCM, and the ELCM COV may seal the canister from atmosphere. 
     Proceeding to  725 , method  700  may include commanding open the CPV, and may further include commanding open the FTIV. In this way, intake manifold vacuum may be communicated to the fuel system and evaporative emissions system. Accordingly, continuing at step  730 , method  700  may include monitoring the vacuum build in the fuel system and evaporative emissions system via the FTPT (e.g.  107 ). It may be understood that the reason for relying on the FTPT is that the method of  FIG. 9  relies on a functional FTPT sensor, and thus the diagnostic discussed at  FIG. 7  allows for determining whether the FTPT is functioning as desired or expected. While not explicitly illustrated, it may be understood that in some examples, the vacuum build may be additionally monitored via the ELCM pressure sensor (e.g.  183 ). It may be understood that monitoring the vacuum build may comprise monitoring the vacuum build for a predetermined threshold duration (e.g. 1 minute or less, 2 minutes or less, etc.) 
     Continuing to  735 , method  700  may include indicating whether the vacuum build has reached or exceeded a predetermined vacuum build threshold. For example, the vacuum build threshold may comprise −8 InH 2 O, −12 InH 2 O, etc. If, at  735 , it is indicated that the vacuum build has reached the predetermined vacuum build threshold, method  700  may proceed to  740 . At  740 , method  700  may include indicating that the CV1, FTIV, and CPV are not stuck closed, and that there is not a source of gross undesired evaporative emissions stemming from the fuel system and/or evaporative emissions system (which may include a stuck open CV2). In other words, if any one of the CV1, FTIV, and/or CPV were stuck closed, then intake manifold vacuum would fail to reach the FTPT, thus the vacuum build would not be able to reach or exceed the predetermined vacuum build threshold. 
     Continuing to  745 , method  700  may include commanding closed the CPV, and conducting a pressure bleedup test. Specifically, by commanding closed the CPV, the intake manifold vacuum may be sealed from the fuel system and evaporative emissions system, and the fuel system and evaporative emissions system may thus be sealed from engine intake and from atmosphere. Accordingly, pressure in the sealed fuel system and evaporative emissions system may be monitored via the FTPT, and compared to a predetermined bleedup threshold. The bleedup threshold may be a function of one or more of fuel level, ambient temperature, RVP of fuel in the fuel tank, fuel tank size, etc. The predetermined bleedup threshold may relate to a size of a source of undesired evaporative emissions that the diagnostic is testing for. The predetermined bleedup threshold may comprise a non-zero, negative pressure threshold, that is somewhere between the vacuum build threshold and atmospheric pressure. In other examples, the pressure bleedup threshold may comprise a pressure bleedup rate. 
     Accordingly, continuing to  750 , if the pressure in the fuel system and/or evaporative emissions remains below the predetermined pressure bleedup threshold, or rises at a rate slower than the predetermined pressure bleedup rate, then method  700  may proceed to  755 , where an absence of undesired evaporative emissions may be indicated. Alternatively, if the pressure bleedup rises at a rate faster than the predetermined pressure bleedup rate, or exceeds the predetermined pressure bleedup threshold at  750 , then the presence of undesired evaporative emissions may be indicated. It may be understood that the undesired evaporative emissions indicated at step  760  may comprise non-gross undesired evaporative emissions (e.g. 0.02″ source, or 0.04″ or less source) as compared to the gross undesired evaporative emissions (e.g. 0.09″ source or greater) discussed above at step  740 . 
     Whether undesired evaporative emissions are indicated or not, the result may be stored at the controller at  765 , and vehicle operating parameters may be updated. For example, if undesired evaporative emissions are indicated, then it may not be desirable to conduct the ejector system diagnostic of  FIG. 9 , as the results may be confounded due to the source of undesired evaporative emissions stemming from the fuel system and/or evaporative emissions system. Alternatively, an absence of a source of undesired evaporative emissions may enable the ejector system diagnostic of  FIG. 9  to be conducted, provided all conditions are met for doing so. 
     Returning to  735 , if the vacuum build threshold is not reached, then method  700  may proceed to  770 . At  770 , method  700  may include indicating that there may be gross undesired evaporative emissions present in the fuel system and/or evaporative emissions system, that one or more of the CV1, FTIV, or CPV may be stuck closed, and/or that the CV2 may be stuck open. Any one of the above issues may result in the failure of the engine intake manifold vacuum to draw down pressure in the fuel system and evaporative emissions system. 
     Proceeding to  765 , method  700  may include storing the result at the controller, and may further include updating vehicle operating parameters, as discussed above. Specifically, due to the failure of the intake manifold vacuum to draw down pressure in the fuel system and evaporative emissions system to the vacuum build threshold, updating vehicle operating parameters may include preventing the ejector system diagnostic of  FIG. 9  from being conducted. In a circumstance where potential undesired evaporative emissions are indicated and/or that one or more of the CPV and FTIV is stuck closed, updating vehicle operating parameters at  765  may include scheduling a follow-up test in an attempt to further isolate the issue. Such a test may comprise the test diagnostic discussed below at  FIG. 8 . 
     Accordingly, whether an absence of non-gross undesired evaporative emissions is indicated (step  755 ), a presence of non-gross undesired evaporative emissions is indicated (step  760 ), or in response to the failure of the intake manifold vacuum to reach the vacuum build threshold (step  770 ), method  700  may proceed from step  765  to step  775 . At  775 , method  700  may include commanding closed/maintaining closed the CPV, and commanding the ELCM COV to the first position. In this way, pressure in the fuel system and evaporative emissions system may be relieved to atmosphere. Proceeding to  780 , method  700  may include commanding closed the FTIV. Method  700  may then end. 
     Turning now to  FIG. 8  a high level example method is depicted, detailing a diagnostic (referred to herein as ELCM evap test) for determining presence or absence of undesired evaporative emissions stemming from the fuel system and evaporative emissions system, and which can indicate whether the FTIV is stuck closed, the CPV is stuck closed and/or whether one or more of the CV1 and CV2 are stuck open. 
     As discussed, instructions for carrying out method  800  may be executed by a controller, such as controller  166  of  FIG. 1 , based on instructions stored in non-transitory memory, and in conjunction with signals received from sensors of the engine system, such as temperature sensors, pressure sensors, and other sensors described in  FIGS. 1-3D . The controller may employ actuators such as RV (e.g.  186 ), ELCM pump (e.g.  330 ), COV (e.g.  315 ), EOBC valve (e.g.  189 ), CPV (e.g.  158 ), FTIV (e.g.  181 ), etc., to alter states of devices in the physical world according to the method depicted below. 
     Method  800  begins at  805  and may include estimating and/or measuring vehicle operating conditions. Operating conditions may be estimated, measured, and/or inferred, and may include one or more vehicle conditions, such as vehicle speed, vehicle location, etc., various engine conditions, such as engine status, engine load, engine speed, A/F ratio, manifold air pressure, etc., various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc., various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc., as well as various ambient conditions, such as ambient temperature, humidity, barometric pressure, etc. 
     Continuing to  810 , method  800  may include indicating whether conditions are met for conducting the ELCM evap test. Conditions being met may include an indication that a canister purging event is not in progress. Conditions being met may additionally or alternatively include an indication that another (e.g. intake manifold vacuum-based) evap diagnostic is not in progress. Conditions being met may additionally or alternatively include an indication that another diagnostic that relies on the ELCM pump is not in progress. Conditions being met may additionally or alternatively include an indication that a refueling event is not in progress. Conditions being met may include an engine-off condition. For example, conditions being met may include an indication that the vehicle is operating in an electric-only mode, or that the vehicle is stopped and the engine has been pulled down such as may occur at a start/stop event. Conditions being met may additionally or alternatively include a key-off event where the controller is kept awake to conduct the diagnostic of  FIG. 8 . Conditions being met may additionally or alternatively include an indication that the controller has been woken up to specifically conduct the diagnostic. Conditions being met may include an indication that the intake manifold vacuum-based diagnostic of  FIG. 7  returned a result that there may be a source of gross undesired evaporative emissions and/or that one or more of the CPV and FTIV may be stuck closed. 
     If, at  810 , conditions are not met, then method  800  may proceed to  815  where current vehicle operating conditions are maintained, similar to that discussed above at steps  509 ,  615 , and  715  of methods  500 ,  600  and  700 , respectively. Method  800  may then end. 
     Alternatively, responsive to conditions being met at  810  for conducting the ELCM-based evap test, method  800  may proceed to  820 . At  820 , method  800  may include commanding or maintaining the RV in the first RV position, and may further include commanding or maintaining the ELCM COV in the first COV position. Continuing at  825 , method  800  may include activating the ELCM pump in the forward mode, or vacuum-mode, to draw a vacuum across the reference orifice of the ELCM (refer to  FIG. 3A ), to obtain a reference pressure. The ELCM pump may be operated in vacuum-mode for a predetermined duration, and/or until a steady-state pressure as monitored via the ELCM pressure sensor (e.g.  183 ) is indicated. The steady-state pressure or reference pressure may comprise a threshold pressure that may subsequently be used for conducting the diagnostic of  FIG. 8 . 
     Accordingly, responsive to the reference pressure being obtained at  830 , method  800  may proceed to  835 . At  835 , method  800  may include deactivating the ELCM pump to relieve the pressure, then the CPV may be commanded or maintained closed, and the FTIV may be commanded open. Commanding the FTIV open while the ELCM pump is off and the ELCM COV is in the first position may allow fuel system depressurization. Next, the ELCM COV may be commanded to the second COV position, and the ELCM pump may be re-activated in the vacuum-mode of operation. 
     Proceeding to  840 , method  800  may include monitoring the vacuum build. The vacuum build may be monitored via the FTPT (e.g.  107 ) and in some examples, additionally via the ELCM pressure sensor (e.g.  183 ). Continuing to  845 , method  800  may include indicating whether the vacuum build has reached or exceeded the reference pressure. If the reference pressure is reached or exceeded, then method  800  may proceed to  850 , where an absence of degradation stemming from the fuel system and evaporative emissions system may be indicated. Specifically, because the vacuum build was monitored via the FTPT, and because the vacuum build reached or exceed the reference pressure, then the FTIV cannot be stuck closed. Furthermore, because the reference pressure was reached or exceeded, there is not a source of undesired evaporative emissions stemming from the fuel system and evaporative emissions system, otherwise the ELCM pump would not have been able to draw down pressure in the fuel system and evaporative emissions system to the reference pressure. However, there may be the potential for the CPV to be stuck closed. 
     Accordingly, proceeding to  855 , method  800  may include commanding open the CPV. Continuing to  860 , method  800  may include indicating whether a pressure inflection point is indicated. Specifically, commanding open the CPV is expected to increase a size of the evaporative emissions system and fuel system that is being evacuated, to a size that is defined by the two check valves (CV1 and CV2), the ELCM COV, and the fuel system. Accordingly, if the CPV is functioning as desired, a brief decrease in negative pressure (in other words, a brief change to a slightly less negative pressure) may be expected. Accordingly, if, at  860 , such an inflection point is not indicated, method  800  may proceed to  865 , where it may be indicated that the CPV is stuck closed. Such a result may be stored at the controller. 
     Alternatively, returning to  860 , if an inflection point is indicated, method  800  may proceed to  880 . At  880 , method  800  may include indicating whether the vacuum build again reaches or exceeds the reference pressure. Specifically, both the CV1 and CV2 may be expected to close upon vacuum being directed at them from the ELCM pump when the ELCM pump is fluidically coupled to the canister as depicted at  FIG. 1 . Accordingly, if the vacuum does not again build to the reference pressure upon opening the CPV, then method  800  may proceed to  885 , where the CV1 and/or CV2 may be indicated to be stuck open. Such a result may be stored at the controller. Alternatively, if the vacuum build does reach or exceed the reference pressure at  880 , method  800  may proceed to  890 , where it may be indicated that the CPV is not stuck closed and the neither the CV1 nor the CV2 are stuck open. Such results may then be stored at the controller. 
     Returning to  845 , in a situation where the vacuum build failed to reach the reference pressure with the CPV closed, method  800  may proceed to  895 , where the presence of degradation may be indicated. Degradation may include one or more of a stuck closed FTIV (because the FTPT is used to monitor the vacuum build) and a source of undesired evaporative emissions stemming from the fuel system and/or evaporative emissions system. Such results may be stored at the controller. 
     Whether the presence of degradation is indicated at step  895 , the CPV is indicated to be stuck closed at step  865 , the CPV is not indicated to be stuck closed nor is the CV1 nor CV2 at step  890 , or if one or more of the CV1 and CV2 are indicated to be stuck open at  885 , method  800  may proceed to  870 . At  870 , method  800  may include deactivating the ELCM pump, and commanding the ELCM COV to the first COV position. At step  870 , method  800  may further include commanding closed or maintaining closed the CPV. With the COV in the first COV position, pressure in the fuel system and evaporative emissions system may be relieved. 
     Continuing to  875 , method  800  may include commanding closed the FTIV. Proceeding to  880 , method  800  may include updating vehicle operating conditions. Updating vehicle operating conditions may include any one of the following examples. As one example, responsive to the CV1 and/or CV2 being stuck open (step  885 ), the controller may prevent the ejector system diagnostic of  FIG. 9  from being conducted, as the diagnostic relies on a functional CV1, and since the diagnostic of  FIG. 8  indicated the CV1 may be stuck open. As another example, the controller may prevent the ejector system diagnostic of  FIG. 9  from being conducted responsive to the indication that the CPV is stuck closed (see step  865 ). As yet another example, the controller may prevent the ejector system diagnostic of  FIG. 9  from being conducted responsive to the indication of the presence of evaporative emissions system and/or fuel system degradation, as discussed with regard to step  895 . Alternatively, the indication that the FTIV is not stuck closed, that the CPV is not stuck closed, that neither the CV1 nor CV2 is stuck open, and that there is an absence of undesired evaporative emissions stemming from the fuel system and evaporative emissions system, may be permissive for allowing the methodology of  FIG. 9  to be conducted when all conditions are met for doing so. Furthermore, updating vehicle operating conditions at  880  may include setting appropriate MIL(s) to alert the vehicle operator of request(s) to service the vehicle in the case where degradation is determined. 
     As discussed above, boosted engine operation may occur infrequently, and even when requested, may comprise durations of time that are not sufficient to robustly and accurately diagnose proper functionality of the vehicle ejector system. Accordingly, as discussed above, the systems of  FIGS. 1-4B  may enable such diagnostics to be conducted without relying on engine operation. Turning to  FIG. 9 , an example method  900  is shown, illustrating how such a diagnostic may be conducted by relying on a positive pressure with respect to atmospheric pressure being introduced to the ejector system via ELCM pump operation. Specifically, by commanding the RV (e.g.  186 ) to the second position and actuating the ELCM pump to supply positive pressure to the ejector system, the ejector system may be diagnosed as will be elaborated below. 
     As discussed, instructions for carrying out method  900  may be executed by a controller, such as controller  166  of  FIG. 1 , based on instructions stored in non-transitory memory, and in conjunction with signals received from sensors of the engine system, such as temperature sensors, pressure sensors, and other sensors described in  FIGS. 1-3D . The controller may employ actuators such as RV (e.g.  186 ), ELCM pump (e.g.  330 ), COV (e.g.  315 ), EOBC valve (e.g.  189 ), CPV (e.g.  158 ), FTIV (e.g.  181 ), etc., to alter states of devices in the physical world according to the method depicted below. 
     Method  900  begins at  905  and may include estimating and/or measuring vehicle operating conditions. Operating conditions may be estimated, measured, and/or inferred, and may include one or more vehicle conditions, such as vehicle speed, vehicle location, etc., various engine conditions, such as engine status, engine load, engine speed, A/F ratio, manifold air pressure, etc., various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc., various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc., as well as various ambient conditions, such as ambient temperature, humidity, barometric pressure, etc. 
     Proceeding to  910 , method  900  may include indicating whether conditions are met for conducting the ELCM-based boost test. Discussed herein, the ELCM-based boost test may also be referred to as “engine-off boost test.” Conditions being met at  910  may include an engine-off condition. In some examples, the engine-off condition may comprise a start/stop event, where the engine is pulled down in response to vehicle speed dropping below a threshold vehicle speed (e.g. when the vehicle is stopped in traffic, at a stoplight, etc.). In other examples, the engine-off condition may comprise a key-off event where the controller is kept awake to conduct the diagnostic, and after which, the controller may be slept. In still other examples, the engine-off condition may comprise a situation where the engine is woken up at a predetermined time in order to conduct the engine-off boost diagnostic. 
     Conditions being met at  910  may additionally or alternatively include an indication that the EOBC (e.g.  185 ) is not degraded, and that the EOBC valve (e.g.  189 ) is not stuck closed (refer to  FIG. 5 ). Conditions being met at  910  may additionally or alternatively include an indication that the CV3 (e.g.  184 ) is not stuck open (refer to  FIG. 6 ). Conditions being met at  910  may additionally or alternatively include an indication that the CPV (e.g.  158 ) and the FTIV (e.g.  181 ) are not stuck closed, and that at least the CV1 is not stuck open (refer to  FIGS. 7-8 ). Conditions being met at  910  may additionally or alternatively include an indication that there is an absence of sources of undesired evaporative emissions stemming from the fuel system and evaporative emissions system. Conditions being met at  910  may additionally or alternatively include an indication that the canister (e.g.  104 ) is substantially clean (e.g. loaded to less than 5%), so that the diagnostic does not draw an undesirable amount of fuel vapors to the engine (which is off). It may be understood that by conducting the diagnostic while the canister is substantially clean, all fuel vapors desorbed to engine intake may be adsorbed via the AIS HC trap (e.g.  169 ). Conditions being met at  910  may additionally or alternatively include an indication that a drive cycle just prior to a key-off event did not include boosted engine operation, and thus an engine-on boost diagnostic was not able to be conducted. In some examples, the controller may learn particular driving routines over time, or may rely on driving route information input into the onboard navigation system, and thus may be able to predict certain drive cycles that will not encounter boosted engine operation. In such an example, conditions being met may include an engine-off condition (e.g. start/stop event) where it is further indicated that boosted engine operation is predicted not to occur during the current drive cycle. 
     If, at  910 , conditions are not indicated to be met for conducting the engine-off boost diagnostic, method  900  may proceed to  915 . At  915 , method  900  may include maintaining current vehicle operating conditions. For example, if the engine is in operation, then such operation may be maintained and the RV is not commanded to the second RV position. Other parameters such as the current position of the RV, current status of the ELCM pump and ELCM COV, current status of the CPV and FTIV, etc., may be maintained. Method  900  may then end. 
     Returning to  910 , responsive to conditions being met for conducting the engine-off boost test, method  900  may proceed to  920 . At  920 , method  900  may include commanding the RV to the second RV position (refer to  FIG. 2 ). Proceeding to  925 , method  900  may include commanding the EOBC valve open, and commanding the ELCM COV to the second COV position. Furthermore, at  925 , method  900  may include commanding open the CPV and the FTIV. While not explicitly illustrated, in some examples, if there is a positive pressure in the fuel system greater than a threshold positive pressure, then the FTIV may be commanded open with the RV in the first RV position and with the ELCM COV in the first COV position, to vent fuel vapors to the canister until the fuel system is depressurized, and then the RV may be commanded to the second RV position, the COV commanded to the second COV position, the EOBC valve commanded open, and the CPV commanded open. 
     With the RV in the second RV position and the EOBC valve open, it may be understood that the ELCM pump may be fluidically coupled to the conduit (e.g.  148 ) that leads to the ejector system. Furthermore, the ejector system may be fluidically coupled to the evaporative emissions system and fuel system due to the open CPV and FTIV. Still further, it may be understood that the fuel system and the evaporative emissions system may be sealed from atmosphere, due to the position of the RV (refer to the position of the RV at  FIG. 2 ). 
     Accordingly, proceeding to  930 , method  900  may include activating the ELCM pump in the pressure mode, or reverse mode, of operation. In this way, positive pressure may be directed through the EOBC and into the ejector system, which may generate a vacuum that is applied on the fuel system and evaporative emissions system. 
     Proceeding to  935 , method  900  may include indicating whether the vacuum build is greater than a threshold vacuum build. In some examples, the threshold vacuum build may comprise the same threshold vacuum build as that referred to above at  FIGS. 7-8 . However, in other examples the threshold vacuum build may be different, without departing from the scope of this disclosure. In some examples, the threshold vacuum build may be a function of fuel level in the fuel tank, fuel tank and/or fuel temperature, ambient temperature, fuel RVP, etc. For example, the vacuum threshold may be made less negative as fuel vaporization increases, which may be dependent on ambient temperature and/or fuel temperature, fuel level, fuel RVP, etc. It may be understood that, because the ELCM is coupled to the EOBC, the ELCM pressure sensor may not be relied upon for monitoring the vacuum in the fuel system and evaporative emissions system. Accordingly, monitoring the vacuum build at  935  may include monitoring the vacuum build via the FTPT (e.g.  107 ). It may be understood that the monitoring of the vacuum build at  935  may comprise monitoring the vacuum build for a predetermined duration (e.g. 1 minute or less, 2 minutes or less, 3 minutes or less, etc.). 
     Continuing to  937 , method  900  may include indicating whether the vacuum build has reached or exceeded (e.g. become more negative than) the threshold vacuum build. If so, then method  900  may proceed to  940 . At  940 , method  900  may include indicating an absence of ejector system degradation. In other words, because the threshold vacuum build was reached or exceeded at  937 , it may be understood that the CV2 opened to communicate vacuum from the ejector system to the fuel system and evaporative emissions system, and the communication of vacuum from the ejector system implies that the ejector (e.g.  140 ) is functioning as desired. Such a result may be stored at the controller. 
     Returning to  937 , in the event that the vacuum build does not reach or exceed the threshold vacuum build, method  900  may proceed to  960 . At  960 , method  900  may include indicating ejector system degradation. Specifically, either the ejector or the CV2 may be degraded. For example, a stuck closed CV2 may result in the vacuum build failing to reach or exceed the threshold vacuum build. Additionally or alternatively, a malfunctioning ejector may be the reason for the vacuum not reaching or exceeding the threshold vacuum build. Such a result may be stored at the controller. 
     Whether the diagnostic indicates that the ejector system is functioning as desired (step  940 ), or is degraded (step  960 ), method  900  may proceed to  945 . At  945 , method  900  may include deactivating the ELCM pump. Continuing to  950 , method  900  may include commanding the RV to the first position, commanding the ELCM COV to the first COV position, and commanding both the CPV and the EOBC valve closed. In this way, the fuel system and evaporative emissions system may be coupled to atmosphere (refer to  FIG. 1  and  FIG. 3C ), so as to relieve any vacuum in the fuel system and evaporative emissions system. 
     Proceeding to  955 , method  900  may include commanding closed the FTIV. Continuing to  957 , method  900  may include updating vehicle operating conditions. Responsive to ejector system degradation, a MIL may be illuminated at the vehicle dash, alerting the vehicle operator of a request to have the vehicle serviced. Furthermore, in response to ejector system degradation, in some examples boosted engine operation may be disabled. However, in other examples, boosted engine operation may be maintained, but purging under boosted engine operation may be discontinued. Method  900  may then end. 
     As discussed above with regard to  FIG. 9 , in some examples conditions may not be met for conducting the engine-off boost test diagnostic, provided that an engine-on boost diagnostic was able to be conducted during a drive cycle just prior to a key-off event, for example. In another example, if an ejector system diagnostic was conducted under boosted engine operation and then a start/stop event is encountered, conditions may not be met for conducting the engine-off boost diagnostic since an engine-on boost diagnostic has already been conducted. Thus, it may be understood that in some examples, a method may include in a first condition, conducting an engine-on boost diagnostic when conditions are met for doing so, and in a second condition, conducting an engine-off boost diagnostic when conditions are met for doing so. Conditions being met for the second condition may include an indication that the engine-on boost diagnostic was not conducted, or is predicted to not be conducted, for a particular drive cycle, and thus, an engine-off boost diagnostic may be scheduled. 
     Accordingly, turning to  FIG. 10 , an engine-on boost diagnostic will be briefly discussed. As discussed, instructions for carrying out method  1000  may be executed by a controller, such as controller  166  of  FIG. 1 , based on instructions stored in non-transitory memory, and in conjunction with signals received from sensors of the engine system, such as temperature sensors, pressure sensors, and other sensors described in  FIGS. 1-3D . The controller may employ actuators such as RV (e.g.  186 ), ELCM pump (e.g.  330 ), COV (e.g.  315 ), EOBC valve (e.g.  189 ), CPV (e.g.  158 ), FTIV (e.g.  181 ), etc., to alter states of devices in the physical world according to the method depicted below. 
     Method  1000  begins at  1005  and may include estimating and/or measuring vehicle operating conditions. Operating conditions may be estimated, measured, and/or inferred, and may include one or more vehicle conditions, such as vehicle speed, vehicle location, etc., various engine conditions, such as engine status, engine load, engine speed, A/F ratio, manifold air pressure, etc., various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc., various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc., as well as various ambient conditions, such as ambient temperature, humidity, barometric pressure, etc. 
     Continuing to  1010 , method  1000  may include indicating whether conditions are met for conducting an engine-on boost diagnostic. Conditions being met may include an indication of boosted engine operation, for example. In some examples, conditions being met may include a prediction that the boosted engine operation will continue for a duration of time sufficient to conduct the engine-on boost diagnostic. The prediction may be based on one or more of learned driving routines, information input into the onboard navigation system, level of boost requested, etc. In some examples, conditions being met may include an indication that neither the CPV nor FTIV is stuck closed, that at least the CV1 is not stuck open, and that there is an absence of undesired evaporative emissions present in the fuel system and evaporative emissions system (refer to  FIGS. 7-8 ) (although in other examples it may be understood that the engine-on boost diagnostic may be used for determining the presence or absence of undesired evaporative emissions, without departing from the scope of this disclosure). 
     If, at  1010 , conditions are not indicated to be met for conducting the engine-on boost diagnostic, method  1000  may proceed to  1015 , where current vehicle operating status may be maintained. Specifically, if the engine is not in operation, then such a condition may be maintained. Alternatively, engine operation may be maintained in its current status provided the engine is operating. Current status of valves including but not limited to the CPV, FTIV, RV, ELCM COV, etc., may be maintained. Method  1000  may then end. 
     Returning to  1010 , responsive to conditions being met for the engine-on boost diagnostic, method  1000  may proceed to  1020 . At  1020 , method  1000  may include commanding the RV to the first RV position, commanding the EOBC valve closed, and commanding the ELCM COV to the second COV position. In this way, the fuel system and evaporative emissions system may be sealed from atmosphere. While not explicitly illustrated, it may be understood that in some examples, the engine-on boost diagnostic may include commanding open the FTIV as well, however, because the ELCM is fluidically coupled to the canister, the ELCM pressure sensor may be relied upon for the engine-on boost diagnostic, which may enable the FTIV to remain closed in other examples. In examples where the FTIV is commanded open, either the FTPT or the ELCM pressure sensor (or both) may be relied upon for conducting the engine-on boost diagnostic. 
     Proceeding to  1025 , method  1000  may include commanding open the CPV. In this way, the ejector system may be fluidically coupled to the evaporative emissions system (and fuel system if the FTIV is additionally commanded open). Continuing at  1030 , method  1000  may include monitoring the vacuum build resulting from boosted engine operation providing positive pressure to the ejector system, and the ejector system in turn communicating a negative pressure with respect to atmospheric pressure on the evaporative emissions system (provided the ejector system is functioning as desired or expected). 
     Proceeding to  1035 , method  1000  may include indicating whether the vacuum build is greater than a threshold vacuum build. In some examples, the threshold vacuum build may comprise the same threshold vacuum build as that discussed above with regard to  FIGS. 7-9 . However, in other examples, the threshold vacuum build may be different without departing from the scope of this disclosure. 
     If, at  1035 , the threshold vacuum build is reached or exceeded, method  1000  may proceed to  1040 . At  1040 , method  1000  may include indicating the absence of ejector system degradation. Alternatively, if the vacuum build does not reach or exceed the threshold vacuum build, then method  1000  may proceed to  1055 , where the presence of ejector system degradation may be indicated. The results may be stored at the controller. 
     Whether degradation is indicated or not, method  1000  may proceed to  1045 . At  1045 , method  1000  may include commanding the ELCM COV to the first COV position, and the CPV may be commanded closed. In this way the evaporative emissions system (and fuel system if the FTIV is also commanded open) may be coupled to atmosphere, to relieve any vacuum introduced to the fuel system and/or evaporative emissions system. In a case where the FTIV is open, then the FTIV may be commanded closed responsive to pressure in the fuel system and evaporative emissions system being relieved to atmosphere. 
     Continuing to  1050 , method  1000  may include updating vehicle operating parameters. Specifically, in a case where degradation is indicated, a MIL may be illuminated at the vehicle dash to alert the vehicle operator of a request to service the vehicle. Furthermore, in a case where ejector system degradation is indicated, in one example boosted engine operation may be prevented until the issue is mitigated, while in other examples boosted engine operation may be allowed, but purging under boosted engine operation may be discontinued. Method  1000  may then end. 
     Turning now to  FIG. 11 , depicted is an example method  1100  for purging the canister under intake manifold vacuum conditions. While it is appreciated that purging the canister may also be conducted under boosted engine operation, as recognized herein boosted operation may comprise short durations and/or be infrequent, and thus presented here is a method for purging the canister under intake manifold vacuum conditions. As one condition for entry in the engine-off boost test is that the canister is substantially free of stored fuel vapors, depicted here is methodology to clean the canister under intake manifold vacuum conditions. 
     As discussed, instructions for carrying out method  1100  may be executed by a controller, such as controller  166  of  FIG. 1 , based on instructions stored in non-transitory memory, and in conjunction with signals received from sensors of the engine system, such as temperature sensors, pressure sensors, and other sensors described in  FIGS. 1-3D . The controller may employ actuators such as RV (e.g.  186 ), ELCM pump (e.g.  330 ), COV (e.g.  315 ), EOBC valve (e.g.  189 ), CPV (e.g.  158 ), FTIV (e.g.  181 ), etc., to alter states of devices in the physical world according to the method depicted below. 
     Method  1100  begins at  1105  and may include estimating and/or measuring vehicle operating conditions. Operating conditions may be estimated, measured, and/or inferred, and may include one or more vehicle conditions, such as vehicle speed, vehicle location, etc., various engine conditions, such as engine status, engine load, engine speed, A/F ratio, manifold air pressure, etc., various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc., various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc., as well as various ambient conditions, such as ambient temperature, humidity, barometric pressure, etc. 
     Proceeding to  1110 , method  1100  may include indicating whether conditions are met for purging the canister. Conditions being met may include a canister loading state greater than a predetermined canister loading state, and/or an indication that a refueling event has occurred which has loaded the canister to some extent, but that a canister purging operation has not yet subsequently been conducted. Conditions being met may additionally or alternatively include an indication of an intake manifold vacuum greater than a predetermined threshold intake manifold vacuum. The predetermined threshold intake manifold vacuum may comprise a non-zero, negative pressure threshold with respect to atmospheric pressure, sufficient for purging vapors from the canister, for example. 
     If, at  1110 , conditions are not met for purging the canister, method  1110  may proceed to  1115 . At  1115 , method  1100  may include maintaining current vehicle operating conditions. For example, engine operation may be maintained as is provided the engine is operating, valves including but not limited to the FTIV, CPV, RV, ELCM COV, etc., may be maintained in their current respective states. The ELCM pump may be maintained in its current operational state, etc. Method  1100  may then end. 
     Alternatively, responsive to an indication that purging conditions are met at  1110 , method  1100  may proceed to  1120 . At  1120 , method  1100  may include commanding the RV to the first RV position, and may further include commanding the ELCM COV to the first COV position. Proceeding to  1125 , method  1100  may include commanding open the CPV. At  1130 , method  1100  may include purging the contents of the canister to engine intake for combustion. While not explicitly illustrated, it may be understood that during the purging air/fuel ration may be monitored, for example via the exhaust gas sensor (e.g.  125 ), so that an amount of fuel vapors being purged from the canister to engine intake may be learned over time. The controller may adjust one or more of fuel injection amount and/or frequency, throttle position, spark timing, etc., to compensate for the fuel vapors being purged to engine intake, in order to maintain a desired air-fuel ratio during the purging event. When an appreciable amount of fuel vapors is no longer being inferred to be inducted to the engine, then it may be indicated that the canister is substantially free of fuel vapors. Accordingly, at step  1135 , method  1100  may include indicating whether the canister is substantially free (e.g. loaded to 5% or less) of fuel vapors. 
     If, at  1135 , it is indicated that the canister is substantially free of fuel vapors, method  1100  may proceed to  1140 , where the CPV may be commanded closed. The RV and the ELCM COV may be maintained in their current states. Continuing to  1145 , method  1100  may include updating vehicle operating parameters, which may include updating the loading state of the canister stored at the controller. A canister purging schedule may additionally be updated as a function of the purging event having taken place. Method  1100  may then end. 
     Thus, discussed herein, a method may comprise while an engine of a vehicle is off and a set of predetermined conditions are met, directing a positive pressure with respect to atmospheric pressure into an ejector system to communicate a negative pressure with respect to atmospheric pressure on a fuel system and an evaporative emissions system. The method may include indicating that the ejector system is degraded in response to the negative pressure not reaching a vacuum build threshold. 
     For such a method, directing the positive pressure into the ejector system may further comprise commanding a routing valve to a second routing valve position to selectively couple a pump to the ejector system by way of an engine-off boost conduit, where commanding the routing valve to a first routing valve position alternatively selectively couples the pump to a vent line stemming from a fuel vapor storage canister positioned in the evaporative emissions system. Responsive to the indication that the ejector system is degraded, the method may include preventing purging of fuel vapors from the fuel vapor storage canister under boosted engine operation conditions. In such a method, directing the positive pressure into the ejector system may further comprise commanding open an engine-off boost conduit valve positioned in the engine-off boost conduit upstream of the ejector system. In such a method, the set of predetermined conditions may include at least an indication that the engine-off boost conduit is free from degradation, and an indication that the engine-off boost conduit valve is not stuck closed. 
     For such a method, the method may further comprise a conduit that receives the positive pressure, the conduit positioned upstream of the ejector system, where the conduit includes a check valve positioned between the ejector system and an engine intake conduit, wherein the check valve functions to prevent the positive pressure from being communicated to the engine intake conduit. In such an example, the set of predetermined conditions may include at least an indication that the check valve is not stuck open. 
     For such a method, directing the positive pressure to the ejector system to communicate the negative pressure with respect to atmospheric pressure on the fuel system and the evaporative emissions system may further comprise commanding open a canister purge valve positioned in a purge conduit that couples the evaporative emissions system to the ejector system. In such an example, the set of predetermined conditions may include at least an indication that the canister purge valve is not stuck closed. 
     For such a method, directing the positive pressure to the ejector system to communicate the negative pressure with respect to atmospheric pressure on the fuel system and the evaporative emissions system may further comprise commanding open a fuel tank isolation valve that selectively fluidically couples the fuel system to the evaporative emissions system. In such an example, the set of predetermined conditions may include at least an indication that the fuel tank isolation valve is not stuck closed. 
     For such a method, indicating that the ejector system is degraded in response to the negative pressure not reaching the vacuum build threshold may further comprise monitoring the negative pressure via a pressure sensor positioned in the fuel system. 
     For such a method, the set of predetermined conditions may include at least an indication of an absence of a source of undesired evaporative emissions stemming from the fuel system and the evaporative emissions system. 
     For such a method, the method may further comprise a first check valve positioned between an intake manifold of the engine and the evaporative emissions system. In such an example, the set of predetermined conditions may include at least an indication that the first check valve is not stuck open. 
     For such a method, directing the positive pressure to the ejector system to communicate the negative pressure on the fuel system and the evaporative emissions system may further comprise sealing the fuel system and the evaporative emissions system from atmosphere. 
     Another example of a method comprises during a condition where an engine of a vehicle is not combusting air and fuel, selectively fluidically coupling a pump positioned in a vent line stemming from a fuel vapor storage canister to an ejector system, routing a positive pressure with respect to atmospheric pressure into the ejector system via the pump in order to reduce a pressure in a fuel system and an evaporative emissions system of the vehicle, and indicating that the ejector system is not degraded responsive to the pressure in the fuel system and the evaporative emissions system being reduced to a vacuum build threshold. 
     In such a method, selectively fluidically coupling the pump to the ejector system may further comprise commanding a routing valve from a first routing valve position to a second routing valve position, where the second routing valve position further comprises sealing the fuel system and the evaporative emissions system upstream of the fuel vapor storage canister from atmosphere. 
     In such a method, the method may further comprise preventing the positive pressure from being routed into an engine intake conduit by a check valve positioned in a conduit upstream of the ejector system that receives the positive pressure being routed to the ejector system. 
     In such a method, routing the positive pressure to the ejector system may further comprise an indication that the fuel vapor storage canister is substantially free from fuel vapors. 
     In such a method, the method may further comprise capturing fuel vapors released from the fuel vapor storage canister during routing the positive pressure to the ejector system via an air intake hydrocarbon trap positioned in an intake manifold of the engine. 
     Turning now to  FIG. 12 , an example timeline  1200  for conducting diagnostics on the EOBC according to the method of  FIG. 5 , is shown. Timeline  1200  includes plot  1205 , indicating whether conditions are met (yes or no) for conducting the EOBC diagnostic, over time. Timeline  1200  further includes plot  1210 , indicating whether the RV (e.g.  186 ) is in the first RV position or the second RV position, over time. Timeline  1200  further includes plot  1215 , indicating whether the ELCM COV (e.g.  315 ) is in the first COV position or the second COV position, over time. Timeline  1200  further includes plot  1220 , indicating whether the EOBC valve (e.g.  189 ) is open or closed, over time. Timeline  1200  further includes plot  1225 , indicating whether the ELCM pump (e.g.  330 ) is off, or operating in the forward mode, otherwise referred to as the vacuum-mode, over time. Timeline  1200  further includes plot  1230 , indicating whether pressure as monitored via the ELCM pressure sensor (e.g.  183 ), is at atmospheric pressure, or at a negative pressure with respect to atmospheric pressure, over time. Timeline  1200  further includes plot  1235 , indicating whether there is EOBC degradation (yes or no), over time. Timeline  1200  further includes plot  1240 , indicating whether the EOBC valve is stuck closed (yes or no), over time. 
     At time t 0 , conditions are not yet indicated to be met for conducting the EOBC diagnostic (plot  1205 ). Accordingly, the RV is configured in the first RV position (plot  1210 ), the ELCM COV is configured in the first COV position (plot  1215 ), and the EOBC valve is closed (plot  1220 ). The ELCM pump is off (plot  1225 ), and pressure as monitored via the ELCM pressure sensor indicates atmospheric pressure, consistent with the evaporative emissions system being fluidically coupled to atmosphere. EOBC degradation is not indicated (plot  1235 ), and the EOBC valve is not current indicated to be stuck closed (plot  1240 ). 
     At time t 1 , conditions are indicated to be met for conducting the EOBC diagnostic (refer to step  506  of method  500 ). Accordingly, at time t 2 , the RV is commanded to the second RV position and the EOBC valve is maintained closed. At time t 3 , the ELCM pump is commanded on in the forward mode, or in other words, the vacuum mode of operation. Accordingly, with the ELCM COV in the first COV position and the ELCM pump activated in the vacuum mode, the ELCM pump draws a vacuum across the reference orifice (refer to  FIG. 3A ). Accordingly, the ELCM pressure sensor registers a decrease in pressure between time t 3  and t 4 , and the pressure that is reached, indicated by dashed line  1231 , comprises the reference pressure that will be used for the EOBC diagnostic. 
     With the reference pressure established by time t 4 , the ELCM pump is deactivated, and pressure as monitored via the ELCM pressure sensor rapidly returns to atmospheric pressure between time t 4  and t 5 . At time t 5 , the ELCM COV is commanded to the second position, and again the ELCM pump is activated in the vacuum mode of operation. In this way, a vacuum is drawn on the EOBC between time t 5  and t 6 . At time t 6 , the vacuum reaches the reference pressure. Accordingly, EOBC degradation is not indicated. 
     With an absence of EOBC degradation indicated at time t 6 , the EOBC valve is commanded open. Responsive to commanding the EOBC valve open, pressure as monitored via the ELCM pressure sensor rapidly returns to atmospheric pressure between time t 6  and t 7 . Because the commanding open of the EOBC valve resulted in pressure in the EOBC line being relieved, it is indicated that the EOBC valve is not stuck closed. If the EOBC valve were stuck closed, then the pressure relief would not be expected upon the commanding open of the EOBC valve. 
     With pressure in the EOBC at atmospheric pressure at time t 7 , the EOBC valve is commanded closed, and conditions are no longer indicated to be met for conducting the EOBC diagnostic. Furthermore, the ELCM COV is commanded to the first COV position. At time t 8 , the RV is commanded back to the first RV position. In this way, with the ELCM COV in the first COV position and the RV in the first RV position, the evaporative emissions system may be coupled to atmosphere for at least the duration comprising time t 8  to time t 9 . 
     Turning now to  FIG. 13 , an example timeline  1300  for diagnosing the CV3 (e.g.  184 ) according to the method of  FIG. 6 , is shown. Timeline  1300  includes plot  1305 , indicating whether conditions are met (yes or no) for conducting the CV3 diagnostic, over time. Timeline  1300  further includes plot  1310 , indicating whether the RV (e.g.  186 ) is in the first RV position or the second RV position, over time. Timeline  1300  further includes plot  1315 , indicating whether the ELCM COV (e.g.  315 ) is in the first COV position or the second COV position, over time. Timeline  1300  further includes plot  1320 , indicating whether the EOBC valve (e.g.  189 ) is open or closed, over time. Timeline  1300  further includes plot  1325 , indicating whether the ELCM pump (e.g.  330 ) is off, or is operating in the reverse mode, also referred to as the pressure-mode, over time. Timeline  1300  further includes plot  1330 , indicating pressure in the intake conduit (e.g.  118 ), as monitored via a pressure sensor (e.g.  117 ) positioned therein, over time. Timeline  1300  further includes plot  1335 , indicating whether the CV3 is stuck open (yes or no), over time. 
     At time t 0 , conditions are not yet indicated to be met for conducting the CV3 diagnostic (plot  1305 ). The RV is in the first RV position (plot  1310 ), and the ELCM COV is commanded to the first COV position (plot  1315 ). The EOBC valve is closed (plot  1320 ), and the ELCM pump is off (plot  1325 ). Pressure in the intake conduit (e.g.  118 ) downstream of the CAC (e.g.  156 ) is at atmospheric pressure (plot  1330 ). At time t 0 , the CV3 is not indicated to be stuck open. 
     At time t 1 , conditions are indicated to be met for conducting the CV3 diagnostic (refer to step  610  of method  600 ). Accordingly, at time t 2  the RV is commanded to the second RV position. At time t 3 , the ELCM COV is commanded to the second position, at time t 4  the EOBC valve is commanded open to fluidically couple the EOBC to the conduit (e.g.  148 ) that leads to the ejector system, and at time t 5 , the ELCM pump is commanded to operate in the reverse mode of operation, also referred to herein as the pressure mode of operation. 
     With the ELCM pump operating to pressurize the EOBC, and with the EOBC valve open, it may be understood that if the CV3 were open, a pressure change would be indicated via the pressure sensor (e.g.  117 ) positioned in the intake conduit. However, between time t 5  and t 6 , no pressure change is indicated, and accordingly pressure in the intake conduit remains below the intake conduit pressure change threshold (refer to step  640  of method  600 ), represented by dashed line  1331 . 
     At time t 6 , the predetermined duration for conducting the CV3 diagnostic elapses, and accordingly, conditions are no longer met for conducting the CV3 diagnostic. As the pressure in the intake conduit remained below the intake conduit pressure change threshold, it is indicated that the CV3 is not stuck open. With conditions no longer being indicated to be met for conducting the diagnostic, the ELCM pump is commanded off. At time t 7 , the EOBC valve is commanded closed. Next, at time t 8 , the ELCM COV is commanded to the first COV position, and then at time t 9  the RV is commanded to the first RV position. Between time t 9  and t 10 , with the ELCM COV in the first COV position and the RV in the first RV position, the evaporative emissions system is coupled to atmosphere. 
     Turning now to  FIG. 14 , depicted is example timeline  1400 , illustrating how the ELCM pump may be used to provide an indication as to whether the CPV and/or FTIV is stuck closed, whether the CV1 and/or CV2 is stuck open, and whether there is a source of undesired evaporative emissions present in the fuel system and/or evaporative emissions system, according to the method of  FIG. 8 . Timeline  1400  includes plot  1405 , indicating whether conditions are met for conducting the ELCM evap test (plot  1405 ), over time. Timeline  1400  further includes plot  1410 , indicating whether the RV (e.g.  186 ) is in the first RV position or the second RV position, over time. Timeline  1400  further includes plot  1415 , indicating whether the ELCM COV (e.g.  315 ) is in the first COV position, or the second COV position, over time. Timeline  1400  further includes plot  1420 , indicating whether the ELCM pump (e.g.  330 ) is off, or is operating in the forward mode, also referred to as the vacuum-mode of operation, over time. Timeline  1400  further includes plot  1425 , indicating pressure as monitored via the ELCM pressure sensor (e.g.  183 ), over time. Timeline  1400  further includes plot  1430 , indicating pressure as monitored via the FTPT (e.g.  107 ), over time. Timeline  1400  further includes plot  1435 , indicating whether the FTIV (e.g.  181 ) is commanded open, or closed, over time. Timeline  1400  further includes plot  1440 , indicating whether the CPV (e.g.  158 ) is commanded open, or closed, over time. Timeline  1400  further includes plot  1445 , indicating whether the CPV is indicated to be stuck closed (yes or no), over time. Timeline  1400  further includes plot  1450 , indicating whether the CV1 and/or CV2 is indicated to be stuck open (yes or no), over time. Timeline  1400  further includes plot  1455 , indicating whether the FTIV is indicated to be stuck open (yes or no), over time. 
     At time t 0 , conditions are not yet met for conducting the diagnostic (plot  1405 ). The RV is commanded to the first position (plot  1410 ), and the ELCM COV is commanded to the first COV position (plot  1415 ). The ELCM pump is off (plot  1420 ), and pressure as monitored via the ELCM pressure sensor (e.g.  183 ), is at atmospheric pressure. Furthermore, the FTIV is closed (plot  1435 ), yet pressure in the fuel tank is also near atmospheric pressure (plot  1430 ). The CPV is also closed (plot  1440 ) at time t 0 . At time t 0 , there is no indication that the CPV is stuck closed (plot  1445 ), there is no indication that the FTIV is stuck closed (plot  1455 ), and there is no indication that the CV1 and/or CV2 are stuck open (plot  1450 ). 
     At time t 1 , conditions are indicated to be met for conducting the diagnostic (refer to step  810  of method  800 ). Accordingly, the ELCM COV is maintained in the first COV position, and the ELCM pump is activated in the forward mode, also referred to herein as the vacuum-mode of operation. Accordingly, a vacuum is drawn across the reference orifice of the ELCM, and accordingly, between time t 1  and t 2 , pressure as monitored via the ELCM pressure sensor becomes negative with respect to atmospheric pressure. By time t 2 , the pressure reduction has stabilized, and accordingly, the reference pressure is established, the reference pressure indicated by dashed line  1426 . 
     With the reference pressure established at time t 2 , the ELCM pump is deactivated, and pressure rapidly returns to atmospheric pressure as monitored via the ELCM pressure sensor. Then, at time t 3 , the ELCM COV is commanded to the second COV position, the FTIV is commanded open, and the ELCM pump is reactivated in the forward mode. In this way, because the CPV is maintained closed, a vacuum is drawn on the fuel system and evaporative emissions system, up to the CPV. Between time t 3  and t 4 , pressure in the fuel system and evaporative emissions system becomes negative with respect to atmospheric pressure, as monitored by the ELCM pressure sensor (plot  1425 ), and by the FTPT (plot  1435 ). By relying on both pressure sensors, it may be determined as to whether the FTIV is stuck closed or not. For example, if a vacuum develops as indicated by the ELCM pressure sensor, but no vacuum development is indicated by the FTPT, then it may be inferred that the FTIV is stuck closed. 
     At time t 4 , pressure as monitored by both the ELCM pressure sensor and the FTPT reaches the reference pressure, represented by dashed line  1426 . Accordingly, while not explicitly illustrated, it may be understood that because the reference pressure was reached, an absence of undesired evaporative emissions stemming from the fuel system and/or evaporative emissions system is indicated. 
     Next, at time t 4 , the CPV is commanded open. Because the CV1 and CV2 valves are expected to close when a vacuum is applied on them from the ELCM pump operating in vacuum mode to draw a vacuum across the CPV, it may be understood that the act of opening the CPV may effectively increase a size of the space that the ELCM pump is evacuating. Accordingly, if the CV1 and CV2 are functioning as desired, and if the CPV is not stuck closed and instead opens when commanded to do so, a brief pressure change in the direction of atmospheric pressure may be expected. In other words, a pressure inflection point may be observed upon commanding open the CPV. 
     Indeed, between time t 4  and t 5 , pressure changes in the direction of atmospheric pressure, as monitored by the ELCM pressure sensor (plot  1430 ) and as monitored via the FTPT (plot  1435 ). Accordingly, the CPV is not indicated to be stuck closed at time t 5 . 
     With the ELCM pump maintained on to evacuate the evaporative emissions system and fuel system, pressure as monitored via the ELCM pressure sensor and the FTPT again becomes more negative between time t 5  and t 6 , again reaching the reference pressure by time t 6 . Accordingly, the neither the CV1 nor CV2 is indicated to be stuck open. At time t 6 , with the diagnostic having indicated the absence of undesired evaporative emissions, the fact that neither the FTIV nor the CPV is stuck closed, and the fact that neither the CV1 nor the CV2 is stuck open, conditions are no longer indicated to be met for conducting the diagnostic. Accordingly, the ELCM COV is commanded to the first COV position, and the ELCM pump is commanded off. The FTIV and the CPV are maintained open. Accordingly, pressure in the fuel system and evaporative emissions system rapidly returns to atmospheric pressure (refer to plots  1425  and  1430 ). Once the pressure in the fuel system and evaporative emissions system reaches atmospheric pressure at time t 7 , the CPV and FTIV are commanded closed. Accordingly, between time t 7  and t 8 , pressure in the fuel system and pressure in the evaporative emissions system hovers around atmospheric pressure. 
     Turning now to  FIG. 15 , an example timeline  1500  is shown, illustrating how an engine-off boost test may be conducted, according to the methodology of  FIG. 9 . Timeline  1500  includes plot  1505 , indicating whether conditions are met for conducting the engine-off boost test (yes or no), over time. Timeline  1500  further includes plot  1510 , indicating whether the RV (e.g.  186 ) is commanded to the first RV position, or the second RV position, over time. Timeline  1500  further includes plot  1515 , indicating whether the ELCM COV (e.g.  315 ) is commanded to the first COV position, or the second COV position, over time. Timeline  1500  further includes plot  1520 , indicating whether the ELCM pump (e.g.  330 ) is commanded off, or is commanded to the reverse mode of operation, also referred to as the pressure mode of operation, over time. Timeline  1500  further includes plot  1525 , indicating whether the EOBC valve (e.g.  189 ) is closed or open, over time. Timeline  1500  further includes plot  1530 , indicating whether the CPV is open or closed, over time. Timeline  1500  further includes plot  1535 , indicating whether the FTIV is open or closed, over time. Timeline  1500  further includes plot  1540 , indicating pressure as monitored via the FTPT (e.g.  107 ), over time. Timeline  1500  further includes plot  1545 , indicating whether there is an indication of ejector system degradation (yes or no), over time. 
     At time t 0 , conditions are not yet indicated to be met for conducting the engine-off boost test (plot  1505 ). The RV is in the first RV position (plot  1510 ), and the ELCM COV is in the first COV position (plot  1515 ). The ELCM pump is off (plot  1520 ), and the EOBC valve is closed (plot  1525 ). The CPV and the FTIV are both closed (refer to plots  1530  and  1535 , respectively), and the FTPT is near atmospheric pressure (plot  1540 ). As of time t 0 , ejector system degradation is not yet indicated (plot  1545 ). 
     At time t 1 , conditions are indicated to be met for conducting the engine-off boost test (refer to step  910  of method  900 ). Accordingly, at time t 2 , the FTIV is commanded open. In this way, any pressure in the fuel tank may be relieve to atmosphere by way of the canister, with the RV in the first RV position and the ELCM COV in the first COV position. 
     At time t 3 , the RV is commanded to the second RV position. At time t 4  the ELCM COV is commanded to the second COV position, the EOBC valve is commanded open, and the CPV is commanded open. Then, at time t 5 , the ELCM pump is activated in the reverse mode to direct a positive pressure with respect to atmospheric pressure through the EOBC, past the open EOBC valve, and to the ejector system, such that the ejector system may then communicate vacuum to the fuel system and evaporative emissions system via the open CPV and open FTIV. 
     Accordingly, between time t 5  and t 6 , pressure in the fuel system and evaporative emissions system becomes negative with respect to atmospheric pressure (plot  1540 ), and at time t 6  the vacuum build threshold, represented by dashed line  1541 , is reached. Accordingly, ejector system degradation is not indicated at time t 6 . 
     With the vacuum build threshold having been reached at time t 6 , the ELCM pump is commanded off, and the ELCM COV is commanded to the first COV position. At time t 7 , the RV is commanded to the first RV position, thus coupling the fuel system and evaporative emissions system to atmosphere. Accordingly, between time t 7  and t 9 , pressure in the fuel system and evaporative emissions system returns to atmospheric pressure. At time t 8 , while pressure is returning to atmospheric pressure, the EOBC valve is commanded closed. Once pressure reaches atmospheric pressure in the fuel system and evaporative emissions system at time t 9 , the FTIV is commanded closed. Pressure in the sealed fuel system hovers around atmospheric pressure between time t 9  and t 10 . 
     In this way, an ejector system configured to deliver vacuum to a fuel system and/or evaporative emissions system under boosted engine operation, may be able to be diagnosed as to whether the ejector system if functioning as desired or expected, even under situations of reduced opportunity to conduct the diagnostic under boosted engine operation conditions. In other words, the diagnostics discussed herein may enable diagnosis of the ejector system functionality without relying on engine operation. The ability to conduct such an engine-off boost diagnostic on the ejector system may improve completion rates for ejector system diagnostics, particularly for hybrid vehicles with limited engine run time, and for vehicles for which boosted engine operation is infrequently encountered and/or where boosted engine operation timeframes are of a short duration (e.g. 1-3 seconds). 
     The technical effect is that by including a RV (e.g.  186 ) that enables an ELCM to be selectively fluidically coupled to the fuel vapor storage canister under certain conditions, and to the EOBC (e.g.  185 ) under other conditions, the ELCM may be selectively utilized to route positive pressure to the ejector system while the engine is off, which may enable diagnosing of the ejector system even when engine-on boost conditions are not encountered for particular drive cycles. Another technical effect is that by including the CV3 (e.g.  184 ), the positive pressure may be routed to the ejector system and not to the intake conduit. Yet another technical effect is that, by indicating that the CV3 is not stuck open, that the CPV is not stuck closed, that the FTIV is not stuck closed, that the EOBC valve is not stuck closed, that at least the CV1 is not stuck open, that the fuel system and evaporative emissions system are free from undesired evaporative emissions, and that the EOBC is not degraded, the directing of positive pressure to the ejector system and the subsequent monitoring of vacuum build in the fuel system and evaporative emissions system may enable the pinpointing of degradation to the ejector system. 
     The systems described herein, along with the methods discussed herein, may enable one or more systems and one or more methods. In one example, a method comprises while an engine of a vehicle is off and a set of predetermined conditions are met, directing a positive pressure with respect to atmospheric pressure into an ejector system to communicate a negative pressure with respect to atmospheric pressure on a fuel system and an evaporative emissions system; and indicating that the ejector system is degraded in response to the negative pressure not reaching a vacuum build threshold. In a first example of the method, the method further includes wherein directing the positive pressure into the ejector system further comprises commanding a routing valve to a second routing valve position to selectively couple a pump to the ejector system by way of an engine-off boost conduit; wherein commanding the routing valve to a first routing valve position alternatively selectively couples the pump to a vent line stemming from a fuel vapor storage canister positioned in the evaporative emissions system; and wherein responsive to the indication that the ejector system is degraded, preventing purging of fuel vapors from the fuel vapor storage canister under boosted engine operation conditions. A second example of the method optionally includes the first example, and further includes wherein directing the positive pressure into the ejector system further comprises commanding open an engine-off boost conduit valve positioned in the engine-off boost conduit upstream of the ejector system; and wherein the set of predetermined conditions includes at least an indication that the engine-off boost conduit is free from degradation, and an indication that the engine-off boost conduit valve is not stuck closed. A third example of the method optionally includes any one or more or each of the first through second examples, and further comprises a conduit that receives the positive pressure, the conduit positioned upstream of the ejector system, where the conduit includes a check valve positioned between the ejector system and an engine intake conduit, wherein the check valve functions to prevent the positive pressure from being communicated to the engine intake conduit; and wherein the set of predetermined conditions includes at least an indication that the check valve is not stuck open. A fourth example of the method optionally includes any one or more or each of the first through third examples, and further includes wherein directing the positive pressure to the ejector system to communicate the negative pressure with respect to atmospheric pressure on the fuel system and the evaporative emissions system further comprises: commanding open a canister purge valve positioned in a purge conduit that couples the evaporative emissions system to the ejector system; and wherein the set of predetermined conditions includes at least an indication that the canister purge valve is not stuck closed. A fifth example of the method optionally includes any one or more or each of the first through fourth examples, and further includes wherein directing the positive pressure to the ejector system to communicate the negative pressure with respect to atmospheric pressure on the fuel system and the evaporative emissions system further comprises: commanding open a fuel tank isolation valve that selectively fluidically couples the fuel system to the evaporative emissions system; and wherein the set of predetermined conditions includes at least an indication that the fuel tank isolation valve is not stuck closed. A sixth example of the method optionally includes any one or more or each of the first through fifth examples, and further includes wherein indicating that the ejector system is degraded in response to the negative pressure not reaching the vacuum build threshold further comprises monitoring the negative pressure via a pressure sensor positioned in the fuel system. A seventh example of the method optionally includes any one or more or each of the first through sixth examples, and further includes wherein the set of predetermined conditions includes at least an indication of an absence of a source of undesired evaporative emissions stemming from the fuel system and the evaporative emissions system. An eighth example of the method optionally includes any one or more or each of the first through seventh examples, and further comprises a first check valve positioned between an intake manifold of the engine and the evaporative emissions system; and wherein the set of predetermined conditions includes at least an indication that the first check valve is not stuck open. A ninth example of the method optionally includes any one or more or each of the first through eighth examples, and further includes wherein directing the positive pressure to the ejector system to communicate the negative pressure on the fuel system and the evaporative emissions system further comprises sealing the fuel system and the evaporative emissions system from atmosphere. 
     Another example of a method comprises during a condition where an engine of a vehicle is not combusting air and fuel, selectively fluidically coupling a pump positioned in a vent line stemming from a fuel vapor storage canister to an ejector system; routing a positive pressure with respect to atmospheric pressure into the ejector system via the pump in order to reduce a pressure in a fuel system and an evaporative emissions system of the vehicle; and indicating that the ejector system is not degraded responsive to the pressure in the fuel system and the evaporative emissions system being reduced to a vacuum build threshold. In a first example of the method, the method further includes wherein selectively fluidically coupling the pump to the ejector system further comprises commanding a routing valve from a first routing valve position to a second routing valve position, where the second routing valve position further comprises sealing the fuel system and the evaporative emissions system upstream of the fuel vapor storage canister from atmosphere. A second example of the method optionally includes the first example, and further comprises preventing the positive pressure from being routed into an engine intake conduit by a check valve positioned in a conduit upstream of the ejector system that receives the positive pressure being routed to the ejector system. A third example of the method optionally includes any one or more or each of the first through second examples, and further includes wherein routing the positive pressure to the ejector system further comprises an indication that the fuel vapor storage canister is substantially free from fuel vapors. A fourth example of the method optionally includes any one or more or each of the first through third examples, and further comprises capturing fuel vapors released from the fuel vapor storage canister during routing the positive pressure to the ejector system via an air intake hydrocarbon trap positioned in an intake manifold of the engine. 
     An example of a system for a vehicle comprises a pump that is selectively fluidically coupled to a vent line upstream of a fuel vapor storage canister positioned in an evaporative emissions system when a routing valve is commanded to a first routing valve position, and that is alternatively selectively fluidically coupled to an ejector system when the routing valve is commanded to a second routing valve position; and a controller with computer readable instructions stored on non-transitory memory that when executed during an engine-off condition, cause the controller to: command the routing valve to the second position, activate the pump to route a positive pressure to the ejector system; monitor a vacuum generated via the ejector system responsive to routing the positive pressure to the ejector system; and indicate that the ejector system is degraded responsive to the vacuum failing to reach or exceed a vacuum build threshold. In a first example of the system, the system may further comprise a fuel system selectively fluidically coupled to the evaporative emissions system via a fuel tank isolation valve, the fuel system including a fuel tank pressure transducer; and wherein the controller stores further instructions to command open the fuel tank isolation valve and monitor the vacuum generated via the ejector system via the fuel tank pressure transducer. A second example of the system optionally includes the first example, and further includes wherein the pump is fluidically coupled to the ejector system when the routing valve is commanded to the second routing valve position by way of an engine-off boost conduit, the engine-off boost conduit further including an engine-off boost conduit valve; and wherein the controller stores further instructions to command open the engine-off boost conduit valve in order to route the positive pressure to the ejector system. A third example of the system optionally includes any one or more or each of the first through second examples, and further comprises a conduit positioned upstream of the ejector system that receives the positive pressure that is routed to the ejector system; and wherein the conduit further includes a passive check valve that prevents the positive pressure from being routed to an intake conduit of an engine of the vehicle. A fourth example of the method optionally includes any one or more or each of the first through third examples, and further comprises a canister purge valve positioned in a purge conduit that couples the fuel vapor storage canister to an engine intake and to the ejector system; and wherein the controller stores further instructions to command open the canister purge valve when routing the positive pressure to the ejector system. 
     In another representation, a method comprises in a first condition, diagnosing an ejector system of a vehicle during boosted engine operation, and in a second condition, diagnosing the ejector system during an engine-off condition, where the second condition includes an indication that the first condition did not occur during a drive cycle just prior to the engine-off condition. In such a method, the first condition may include selectively coupling an ELCM pump to a vent line stemming from a fuel vapor storage canister by commanding a routing valve to a first routing valve position, and commanding an ELCM COV to a second position to seal the vent line from atmosphere. In such a method, the second condition may include selectively coupling the ELCM pump to the ejector system by way of an engine-off boost conduit, where the second condition further comprises commanding the routing valve to a second routing valve position and activating the ELCM pump to route a positive pressure with respect to atmospheric pressure to the ejector system. 
     Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller. 
     It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein. 
     As used herein, the term “approximately” is construed to mean plus or minus five percent of the range unless otherwise specified. 
     The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.