Patent Publication Number: US-7216614-B2

Title: Fuel supply device for outboard device

Description:
PRIORITY INFORMATION 
   This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2004-270021, filed on Sep. 16, 2004, the entire contents of which is hereby expressly incorporated by reference herein. 
   BACKGROUND OF THE INVENTIONS 
   1. Field of the Inventions 
   The present inventions relate generally to fuel supply devices for an engines, and more particularly, to fuel supply systems for outboard motors that supply fuel to a vapor separator tank positioned adjacent to an engine from a main fuel tank disposed in a hull by a low pressure fuel pump. 
   2. Description of the Related Art 
   Some of the known outboard motor designs include a vapor separator tank disposed within the upper cowling of the outboard motor. For example, Japanese Patent Document JP-A-Hei09-144617, in at least FIG. 2 thereof, discloses such an outboard motor. In this outboard motor, both a vapor separator tank and a low pressure fuel pump are positioned on a side of and adjacent to the engine, within the cowling. 
   The vapor separator tank accumulates fuel to be supplied to the engine, and also has a high pressure fuel pump therein. A high pressure fuel supply conduit is connected to the vapor separator tank to supply the fuel discharged from the high pressure pump to fuel injectors. Also, a high pressure fuel return conduit is connected to the fuel injectors to return the surplus of the fuel to the vapor separator tank. 
   The low pressure fuel pump is used to supply the fuel to the vapor separator tank from the main fuel tank in the hull of the associated boat. The low pressure fuel pump is positioned on a side of and adjacent to the engine, and is mounted on the engine via a bracket. An upstream side low pressure fuel supply conduit is coupled with a fuel suction port of the low pressure fuel pump and extends to the main fuel tank in the cowling. A downstream side low pressure fuel supply conduit is coupled with a discharge port of the low pressure fuel pump and extends to the vapor separator tank. 
   A manually operated primer pump and a fuel filter are situated midway of the upstream side fuel supply conduit. The primer pump is used to supply the fuel to the low pressure fuel pump from the main fuel tank. 
   A switching valve is placed at a fuel inlet port of the vapor separator tank, to which the downstream side low pressure fuel supply conduit is connected, to be opened or closed by a float floating in this tank. The switching valve is closed when a surface of the liquid fuel in the vapor separator tank reaches the preset maximum level. The valve is opened when the surface of the fuel falls to a level lower than the maximum level. As such, the low pressure fuel pump supplies the fuel from the main fuel tank in the hull of the boat to the vapor separator tank in the outboard motor, and the high pressure fuel pump supplies the fuel in the vapor separator tank to the fuel injectors. 
   SUMMARY OF THE INVENTIONS 
   An aspect of at least one of the embodiments disclosed herein includes the realization that an electronic fuel pump can be used to simply a starting procedure for an outboard motor. For example, occasionally, before starting a conventional outboard motor described above, an operator needs to supply fuel to the vapor separator tank from the main fuel tank using the manually operated primer pump. A so-called “dead soak,” is when the operator stops the engine immediately after a full speed running of an associated watercraft and then restarts the engine a preset time later. When the engine is stopped, a temperature within the cowling increases by the heat of the engine under the stopped condition of the watercraft so that the fuel in each fuel passage of the respective conduits vaporizes. In particular, if a fuel that has a high lead vapor pressure is used, or the outboard motor is used under circumstances such that an air temperature or a water temperature is relatively high, an amount of the fuel that vaporizes can be larger. 
   When the fuel in the fuel passages vaporizes as discussed above, the vapor pushes the liquid fuel back to the main fuel tank. Consequently, the fuel passages can be nearly or completely depleted of liquid fuel. If the engine is started under the condition that only a nominal amount of the liquid fuel is in the fuel passages in the low pressure fuel supply system, all of the fuel in the vapor separator tank may be consumed before the fuel in the main fuel tank is supplied to the vapor separator tank by the low pressure fuel pump. As a result, the engine can stall. 
   Thus, in the conventional fuel supply device, if the performs a “dead soak”, the operator needs to supply the fuel to the low pressure fuel supply system using the manually operated primer pump prior to restarting of the engine as described above. This operation of the primer pump can be a burden for the operator because the operator repeatedly grasps and releases a pressurizing portion made of a rubber material by hand. 
   In addition, the primer pump is used when, other than the dead soak type operation, the main fuel tank is replenished with another amount of fuel after the engine completely consumed the fuel in the main fuel tank. This operation of the primer pump can be a similar burden to the operator. 
   Thus, in accordance with an embodiment, a fuel supply device for an outboard motor, wherein a low pressure fuel pump supplies fuel to a vapor separator tank positioned adjacent to an engine from a main fuel tank disposed in a hull of an associated boat can be provided. The fuel supply device can comprise an electrically operated primary fuel pump and a check valve both positioned parallel to each other and between the main fuel tank and the low pressure fuel pump. Additionally, a control device can be connected to the primary fuel pump for operating the primary fuel pump only for a preset fuel supply time when the engine is started. 
   In accordance with another embodiment, an outboard motor can comprise an engine, a cowling disposed over the engine, and a vapor separator tank disposed between the engine and the cowling. A low pressure fuel pump can be configured to supply fuel from a main fuel tank carried by a boat to which the outboard motor is mounted to the vapor separator tank. An electrically operated primary fuel pump and a check valve can both be positioned parallel to each other and between the main fuel tank and the low pressure fuel pump. A control device can be connected to the primary fuel pump and configured to operate the primary fuel pump to pump fuel from the main fuel tank to the vapor separator for a preset time and to prevent the engine from starting for a predetermined time when an operator is attempting to start the engine. 
   In accordance with yet another embodiment, an outboard motor can comprise an engine, a cowling disposed over the engine, and a vapor separator tank disposed between the engine and the cowling. A low pressure fuel pump can be configured to supply fuel from a main fuel tank carried by a boat to which the outboard motor is mounted to the vapor separator tank. An electrically operated primary fuel pump and a check valve can both be positioned parallel to each other and between the main fuel tank and the low pressure fuel pump. Additionally, means can be provided for automatically operating the primary fuel pump to pump fuel from the main fuel tank to the vapor separator for a preset time and to prevent the engine from starting for a predetermined time when an operator is attempting to start the engine. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the inventions will become more apparent upon reading the following detailed description and with reference to the accompanying drawings of embodiments that exemplify the inventions, in which: 
       FIG. 1  is a schematic side elevational view of a fuel supply device of an outboard motor according to an embodiment. 
       FIG. 2  is an enlarged cross sectional view of the powerhead of the outboard motor of  FIG. 1 , and showing a partial sectional and cutaway schematic view of a portion of the fuel supply system within the cowling of the powerhead of the outboard motor. 
       FIG. 3  is a block diagram of the fuel supply system. 
       FIG. 4  is a portion of a flowchart of a method of operating a fuel supply system that can be used with the fuel supply system illustrated in  FIGS. 1–3 . 
       FIG. 5  is another portion of the flowchart partially shown in  FIG. 4 . 
       FIG. 6  is a further portion of the flowchart partially shown in  FIGS. 4 and 5 . 
       FIG. 7  is a still further portion of the flowchart partially shown in  FIGS. 4 and 5 . 
       FIG. 8  is a schematic side elevational view of an outboard motor including a modification to the fuel system shown in  FIG. 1 . 
       FIG. 9  is a schematic side elevational view of an outboard motor including yet another modification to the fuel system shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  is a schematic side elevational view of an outboard motor  1  including a fuel supply system according to an embodiment. The inventions disclosed herein are disclosed in the context of outboard motors because these inventions have particular utility in this context. However, the inventions disclosed herein can also be used in other contexts, including fuel systems for other types of engines used to power other types of vehicles and other types of machines. 
   The outboard motor  1  can include a clamping bracket  2  for mounting it to a transom of an associated hull (not shown). The outboard motor  1  can also include an upper casing  3  and a lower casing  4  both supported by the clamping bracket  2 , an engine  5  disposed above the upper casing  3 , a propeller  6  rotated by the power from the engine  5 , and a cowling  7  that encloses the engine  5  and so forth. 
   The cowling  7  can include a bottom cowling  8  formed generally in the shape of a shallow tray that opens upwardly and is coupled with an upper portion of the upper casing  3 . A top cowling  9  can be used to close the opening defined at the upper end of the bottom cowling  8 . 
   As shown in  FIG. 2 , a seal member  10  can be water-tightly inserted between the bottom cowling  8  and the top cowling  9 . The bottom cowling  8  can be made of an aluminum alloy, while the top cowling  9  can be made of a synthetic resin. 
   As shown in  FIG. 2 , the engine  5  can have a fuel supply device  11  including fuel injectors (not shown). The fuel supply device  11  can also include a high pressure fuel supply system  13  having a vapor separator tank  12 , a low pressure fuel supply system  15  having a low pressure pump  14 , and an electrically operated primer pump  16  (see  FIG. 1 ), which is described below. The electrically operated primer pump  16  can function as a primary fuel pump. 
   The high pressure fuel supply system  13  can comprise the vapor separator tank  12  positioned on a side of the engine  5 , a high pressure fuel pump  18  placed within the vapor separator tank  12 , the fuel injectors (not shown) connected to the high pressure pump  18  through high pressure fuel supply conduits  19 , a pressure regulator  20  for regulating the fuel pressure in the high pressure fuel supply conduits  19  and so forth. However, other configurations and also be used. In some embodiments, a water-cooled fuel cooling unit  22  can be coupled with a portion of a fuel return conduit  21  connecting a downstream side of the pressure regulator  20  and an internal cavity of the vapor separator tank  12 . 
   A float type switching valve  23  can be disposed in the cavity of the vapor separator  12  to close or release a bottom end opening of a fuel inlet port pipe  12   a . The switching valve  23  can close the opening when a liquid surface L in the vapor separator tank  12  is positioned at the highest level shown in  FIG. 2 . The switching valve  23  can release the opening when the liquid surface L can be lowered from the highest level. 
   The fuel inlet port pipe  12   a  can be connected to a low pressure fuel pump  14 , which is described below, through a downstream side low pressure fuel supply conduit  24 . A pipe  25  can be coupled with a top end of the vapor separator tank  12  to guide vapor (fuel as) developed in the cavity of the vapor separator tank  12  to an intake passage of the engine. 
   The high pressure fuel pump  18  draws in the fuel accumulated in the cavity of the vapor separator tank  12  and discharges it to the high pressure fuel supply conduits  19 . The components of the high pressure fuel supply system  13 , including the high pressure fuel pump  18 , can be positioned on a side of and adjacent to the engine  5  within the cowling  7 , although other configurations can also be used. 
   The low pressure fuel pump  14  can be mounted on a side portion of the engine  5  by a support bracket, which is not shown. The low pressure fuel pump  14  can incorporate a drive motor (not shown) therein, and can be mounted on the engine  5  under a condition that an axis of a drive shaft positioned in the drive motor extends generally vertically. However, other orientations can also be used. 
   A top end of the low pressure fuel pump  14  has a fuel discharge port (not shown). The downstream side low pressure supply conduit  24  can be coupled with the fuel discharge port. Meanwhile, a bottom end of the low pressure fuel pump  14  has a fuel suction port (not shown). An upstream side low pressure fuel supply conduit  26 , which will be described below, can be coupled with the fuel suction port. The low pressure fuel pump  14  has a bypass conduit  27  for connecting the fuel suction port and the fuel discharge port with each other. A relief valve  28  can be positioned midway of the bypass conduit  27 . 
   The upstream side low pressure fuel supply conduit  26  connects the fuel suction port of the low pressure fuel pump  14  and a fuel outlet of the main fuel tank  31  of the hull side shown in  FIG. 1  with each other. A portion  26   a  of the conduit  26  extending within the cowling  7  can have a fuel filter unit  32 . As shown in  FIG. 1 , another portion  26   b  of the upstream side low pressure fuel supply conduit  26  extending to the main fuel tank  31  in the hull can have an electrically operated primer pump  16  and a check valve  33 . The fuel filter unit  32  can be mounted on the engine  5  similarly to the low pressure fuel pump  14 , although this mounting arrangement is not shown. 
   The primer pump  16  can have almost the same construction as the low pressure fuel pump  14 , and can be mounted on the hull by a support bracket (not shown). The primer pump  16  and the check valve  33  can be connected to the upstream side low pressure fuel supply conduit  26  so that they extend parallel to each other. 
   The check valve  33  can be configured to only allow the fuel to flow to the outboard motor  1  side from the main fuel tank  31 , and can be mounted on the hull similarly to the primer pump  16 . In this fuel supply device  11 , the primer pump  16  does not function while the engine  5  operates. Thus, under this condition, the fuel supplied to the outboard motor  1  side from the main fuel tank  31  inevitably passes through the check valve  33 . 
   A drive motor (not shown) housed in a housing  16   a  of the primer pump  16  can be connected to a control unit  34  (see  FIG. 1 ) disposed in the outboard motor  1 . As shown in  FIG. 3 , the control unit  34  can include an engine control device  35  configured to control the starting and stopping of the engine  5 , fuel injection amounts and the like, and a primer pump control device  36  for controlling the operation of the primer pump  16 . Although the control device  35  can also be configured to control other operations as well. The engine control device  35  can have the same general construction used for the control devices used for conventional outboard motors, for example, it can include at least one memory device, at least one processor, etc, configured to perform typical outboard motor control operations. In some embodiments, such a controller can also be in the form of a hard-wired control device. 
   In some embodiments, as shown in  FIG. 3 , a main switch  41 , a temperature sensor  42 , a liquid level sensor  43  and an engine speed sensor  44  can be connected to an input side of the primer pump control device  36 . The main switch  41  can be located in an area of the cockpit of the hull, and can be operable, for example, between two positions. That is, when the main switch  41  is operated to be at the first position, a feed circuit of the control unit  34  can be activated, and simultaneously a control operation for the primer pump control device  36 , which is described below, can be started. Meanwhile, when the main switch  41  is changed to the second position beyond the first position, a starter motor (not shown) can start the engine  5 . In some embodiments, the engine  5  will not start until a preparation for the start operation has been finished by the primer pump control device  36 . 
   Various kinds of temperature sensors normally used for conventional outboard motors can be used as the temperature sensor  42 . The temperature sensor  42  can be formed with any one of, or with a combination of a plurality of sensors selected from an engine temperature sensor for detecting a temperature of an outer wall of the engine  5 , an oil temperature sensor for detecting a temperature of lubricant oil, a water temperature sensor for detecting a temperature of cooling water, an intake air temperature sensor for detecting intake air in the intake passage or the like. Other types of sensors can also be used to provide a temperature signal indicative of the temperature of the engine  5 . 
   As shown in  FIG. 1 , the liquid level sensor  43  can be configured to detect a level of the fuel in the main fuel tank  31 . The engine speed sensor  44  can be configured to detect an engine speed based upon a rotation of a crankshaft (not shown), number of ignition times of an ignition system, or the like. 
   As shown in  FIG. 3 , an indicating device  45 , automatic priming lamp  46 , a cranking allowing and prohibiting lamp unit  47 , a residual amount warning lamp  48 , a buzzer  49  and a primer pump drive relay  50  can be connected to an output side of the primer pump control device  36 . The indicating device  45 , all of the lamps and the buzzer  49  can be disposed in the cockpit of the hull, or anywhere in the hull where an operator of the associated boat can see them. The primer pump drive relay  50  can be configured to switch a power supply circuit for the primer pump  16 . 
   As shown in  FIG. 3 , the primer pump control device  36  can have a starter motor operation regulating means  51 , main tank liquid level determining means  52 , engine speed determining means  53 , engine temperature determining means  54 , supply time setting means  55 , supply time extending means  56 , primer pump drive means  57 , a memory  58 , a timer  59  and so forth. However, other components can also be included. 
   The starter motor operation regulating means  51  can be connected to the engine control device  35 , and can be configured to regulate the operation of the starter motor, which is not shown. The main tank liquid level determining means  52  can be configured to determine whether an actual level of the fuel in the main fuel tank  31  detected by the liquid level sensor  43  can be lower than a preset warning level H 2  (see  FIG. 1 ) or not, and also to determine whether the actual level is lower than the minimum level H 1  (see  FIG. 1 ) or not. In addition, the main tank liquid level determining means  52  can be configured to reach the determination that the main fuel tank  31  is empty if the actual level of the fuel is lower than the minimum level H 1  and to store this empty determination result into the memory  58 . 
   The engine speed determining means  53  can be configured to determine whether an engine speed Ne detected by the engine speed sensor  44  is zero or not, and also to determine whether the engine speed Ne is greater than a preset start determining speed nc or not. 
   The engine temperature determining means  54  can be configured to determine whether a temperature of the engine  5  detected by the temperature sensor  42  is greater than a warming up condition determining temperature Tc or not. 
   The supply time setting means  55  can be configured to compute a time (predetermined operation time) for which the primer pump  16  operates, by putting the temperature of the engine  5  detected by the temperature sensor  42  into a predetermined function used for the dead soak operation. 
   The supply time extending means  56  can be configured to exchange the function for the dead soak operation to another function which is different from the function for the dead soak operation if the main fuel tank liquid level determining means  52  determines that the main fuel tank  31  is empty. The function used when the empty determination is made is used to trigger a mode in which the time for which the primer pump  16  operates is extended. 
   The primer pump drive means  57  can be configured to place the primer pump drive relay  50  in an ON condition for the desired operation time set by the supply time setting means  55  to operate the primer pump  16  during the time. 
   With reference to  FIGS. 4–7 , an operation of the primer pump control device  36  is described in detail together with more detailed descriptions of the structure thereof. 
   As shown in  FIG. 4 , upon setting the main switch  41  to the first position and at a step S 1 , the primer pump control device  36  can start its operation. In this operation, the primer pump control device  36  can regulate the engine control device  35  to prohibit the starter motor from starting the engine at a step S 2  while the main switch  41  stays at the first stage position. At a step S 3 , the control device  36  can turn on a red lamp of the cranking allowing and prohibiting lamp unit  47  which indicates the prohibition of the engine start to the operator. Thus, the engine will not start during this mode of operation. 
   Next, at a step S 4 , the main fuel tank liquid level determining means  52  of the control device  36  can determine whether a liquid level H at this moment in the main fuel tank  31  is lower than the warning level H 2  or not. If a sufficient amount of the fuel is present in the main fuel tank  31 , the control device  36  determines “NO” at a step  4 , and turns off the residual amount warning lamp  48  at a next step S 5  if it was already on. 
   Afterwards, at a step S 6 , the engine speed determining means  53  determines whether an engine speed Ne at this moment is zero or not. In this determination, if the engine  5  has already been operating, the control device  36  returns to the step S 4 . If the engine  5  is not running (e.g., the crankshaft of the engine  5  is not rotating), the control device  36  goes to a step S 7  of the flowchart of  FIG. 5 . This is because the primer pump  16  is only operated, in some embodiments, under a condition that the engine  5  is not running. 
   At the step S 7 , the main fuel tank liquid level determining means  52  can determine whether the means  52  have ever determined that the main fuel tank  31  is empty. If the main fuel tank  31  has a sufficient amount of the fuel, the means  52  determines “NO” and the control device  36  goes to a step S 8 . 
   The engine temperature determining means  54 , at the step S 8 , can determine whether a temperature T of the engine  5  at this moment is higher than the warming up condition determining temperature Tc or not. If the temperature T of the engine  5  is lower than the warming up condition determining temperature Tc, the engine  5  is started without the primer pump  16  being used. The control device  36  allows itself to go to a step S 9  only when the temperature T of the engine  5  is higher than the warming up condition determining temperature Tc. 
   At the step S 9 , the supply time setting means  55  set the desired operation time tp of the primer pump  16 . The desired (e.g., a predetermined time) operation time tp at this moment is equal to a time th that is computed by putting the detected engine temperature T into the predetermined function for the dead soak operation. 
   After the predetermined operation time tp is set as discussed, the primer pump drive means  57  operates the primer pump  16  for this predetermined operation time tp at steps S 10 –S 13 . In the event of that the primer pump  16  does not change to the ON condition, the control device  36  goes to a step. S 14  from the step S 11  to make the indicating device  45  show a message regarding this abnormal state and also to stop the entire control from that time onward. If the primer pump  16  changes to the ON condition, the primer pump drive means  57 , at the step S 12 , turn the automatic priming lamp  46  on. The turned-on state of the automatic priming lamp  46  notifies the operator that the primer pump  16  is in operation. 
   As shown in the flowchart of  FIG. 6 , after the primer pump  16  operates for the predetermined operation time tp, the primer pump drive means  57  stops the primer pump  16  at a step S 15 . The primer pump drive means  57  checks the standstill condition of the primer pump  16  (i.e., checks whether the primer pump is stopped) at a step S 16 , and then goes to a step S 17  to turn the automatic priming lamp  46  off. In the event of that the primer pump drive means  57  is not able to confirm the standstill condition of the primer pump  16  at the step S 16 , the primer pump drive means  57  make the buzzer  49  sound at a step S 18 , make the indicating device  45  show a message regarding this abnormal state at a step S 19 , and also stop the entire control from that time onward. 
   After the primer pump  16  is stopped as thus described, if the main fuel tank liquid level determining means  52  has recorded in its memory an “empty determination”, the means  52  purge the memory (e.g., erases the memory) at a step S 20 . The starter motor operation regulating means  51 , at a step S 21 , place the starter motor under the condition that it is ready for operation. In addition, if the temperature T of the engine  5  is determined to be lower than the warming up condition determining temperature Tc at the step S 8 , the control device  36  directly jumps to the step S 21 . 
   After the engine  5  is allowed to be started at the step S 21 , the starter motor operation regulating means  51 , at a step S 22 , turns on a green light of the cranking allowing and prohibiting lamp unit  47  to indicate that the operator is allowed to start the engine. At a step S 23 , the starter motor operation regulating means  51  make the timer  59  start clocking. 
   Afterwards, at steps S 24  and S 25 , the starter motor operation regulating means  51  awaits a moment at which a time tm that the timer  59  counts reaches a preset determination time t 0 , or waits until the start operation of the starter motor is made by the main switch  41  (i.e., the main switch  41  is operated to the second stage position), respectively. Under these circumstances, if the starter motor is not operated in the determination time t 0 , the starter motor operation regulating means  51  again regulates the start operation of the starter motor at a step S 26 , turns the red lamp of the cranking allowing and prohibiting lamp unit  47  at a step S 27 , and stops the timer  59  at a step S 28 . Afterwards, the control device  36  returns to the step S 8  and repeats the steps described above. 
   On the other hand, if the start operation of the starter motor is made, the control device  36  goes to a step S 29  of the flowchart of  FIG. 7  so that the engine speed determining means  53  determines whether an engine speed ne at this moment is greater than the start determining speed nc. If the engine  5  is not started, the control device  36  determines at a step S 30  whether the main switch  41  is placed under the OFF condition or not. If the OFF condition of the main switch  41  is determined, the entire control from that time onward is stopped. Under the condition that the main switch  41  is operated to the first position, the control device  36  returns to the step S 25  to wait for the start operation by the starter motor. 
   If it is determined at the step S 29  that the engine  5  has been started, the starter motor operation regulating means  51  turns off all the lamps of the cranking allowing and prohibiting lamp unit  47  at a step S 31 , stops the timer  59  at a step  32 , and then stops the entire control from that time onward. That is, in the dead soak operation, the fuel supply device  11  of this embodiment operates the primer pump  16  for the time corresponding to the temperature T of the engine  5  to supply the fuel in the main fuel tank  31  to the outboard motor  1  side when the engine is started. 
   If the fuel in the main fuel tank  31  is consumed and the level of the fuel is lowered to the warning level H 2 , the control device  36  determines “YES” at the step S 4  of the flowchart of  FIG. 4 . Under this condition, at a step S 33 , the main fuel tank liquid level determining means  52  turns the residual amount warning lamp  48  on, and determines at a step S 34  whether a level of the fuel in the main fuel tank  31  at this moment is lower than the minimum level H 1 . 
   If the level of the fuel is higher than the minimum level H 1 , the liquid level determining means  52  determine “NO” and the control device  36  goes to a step S 6 . Meanwhile, if the level of the fuel is lower than the minimum level H 1 , the main fuel tank liquid level determining means  52 , at the step S 35 , stores the determination result that the main fuel tank  31  is empty into the memory  58 . In addition, at a step S 36 , the starter motor operation regulating means  51  determines whether the start operation of the starter motor is made by the main switch  41  or not. 
   If the determination is “NO,” the control device  36  returns to the step S 4 . Meanwhile, if the determination is “YES,” the control device  36  goes to the step S 6 . 
   Afterwards, the control device  36  goes to the step S 7  of the flowchart of  FIG. 5  only when the engine speed Ne is zero. The control device  36  determines “YES” at the step S 7  and then goes to a step S 37 . 
   At the step S 37 , the engine temperature determining means  54  detect a temperature T of the engine at this moment. Next, at a step S 38 , the supply time setting means  55  sets a predetermined operation time tp of the primer pump  16  based upon the engine temperature T. The predetermined operation time tp under this condition is set to the time tc computed by putting the engine temperature T at this moment into the function for the predetermined empty determining operation. The predetermined operation time tp at this moment is greater than the predetermined operation time for the dead soak operation. 
   After the predetermined operation time tp is set as discussed above, the control device  36  goes to the step S 10  and repeats the steps described above. 
   As thus described, according to the fuel supply device  11  for the outboard motor  1  in this embodiment, the electrically operated primer pump  16  supplies the fuel to the outboard motor  1  side from the main fuel tank  31  prior to the start of the engine  5 . The vapor in the fuel passages of the low pressure fuel supply system  15  thus is moved to the vapor separator tank  12  so that the fuel passages thereof are filled with the liquid fuel. Therefore, in the outboard motor  1  having the fuel supply device  11  of this embodiment, the low pressure fuel pump  14  can supply the fuel to the internal cavity of the vapor separator tank  12  immediately after the start of the engine  5 . 
   In the fuel supply device  11  of this embodiment, the fuel supply amount of the primer pump  16  varies in accordance with the temperature T of the engine  5 . Because the amount of the vapor developed in the dead soak operation increases in accordance with the temperature T of the engine  5 , an sufficient amount of the fuel can be supplied to the outboard motor  1  using the fuel supply device  11  of this embodiment. 
   In the fuel supply device  11  of this embodiment, the operation time of the primer pump  16  is extended (i.e. is made longer) if the residual amount of the fuel in the main fuel tank  31  is less than the minimum amount. Thus, under such a condition that the residual amount of the fuel in the main fuel tank  31  becomes small and the air is more likely to be sucked into the fuel passages extending between the main fuel tank  31  and the vapor separator tank  12 , the fuel can be sufficiently supplied to the fuel passages prior to the start of the engine  5 . 
   In the fuel supply device  11  of this embodiment, the residual amount warning lamp  48  is turned on when the level of the fuel in the main fuel tank  31  reaches the warning level H 2 . The warning lamp  48  thus can urge the operator to replenish the main fuel tank  31  with the fuel. 
   In the fuel supply device  11  of this embodiment, the fuel supply process by the primer pump  16  can be omitted when the temperature T of the engine  5  at the moment of its start is lower than the warming up condition determining temperature Tc. Thereby, the engine  5  can be quickly started. 
   In the fuel supply device  11  of this embodiment, if the engine  5  is not started within a predetermined time since the primer pump  16  supplied the fuel to the outboard motor  1  side, the primer pump  16  again supplies the fuel in the next start operation of the engine. Therefore, even though the temperature of the interior of the cowling  7  is high, the fuel passages can be filled with the liquid fuel all the time. 
     FIG. 8  illustrates a modification of the fuel supply device described above. In  FIG. 8 , the same or similar members as or to the members described referring to  FIGS. 1–7  are assigned with the same reference numerals or symbols, and detailed descriptions of those members will not be repeated as appropriate. 
   The electrically operated primer pump  16  and the check valve  33  can together be positioned within the main fuel tank  31  of  FIG. 8  under a condition that both members  16 ,  33  are immersed in the fuel. A bottom end (a portion for fuel suction) of the primer pump  16  and a bottom end of the check valve  33  both can have respective strainers  61 ,  62 . 
   A top end of the primer pump  16  and a top end of the check valve  33  can be connected to each other through a connecting pipe  63  that extends generally vertically in the main fuel tank  31 . A downstream end of the connecting pipe  63  can be coupled with the upstream side low pressure fuel supply conduit  26 . Although other configurations can also be used. 
   Because of the construction in this embodiment, the main fuel tank  31  and the outboard motor  1  can be connected to each other through a single upstream side low pressure fuel supply conduit  26 . The fuel supply device  11  according to this embodiment thus can have a simpler structure of the fuel conduits in the hull. Also, because the main fuel tank  31  is the component that supports the primer pump  16  and the check valve  33 , no other support bracket is necessary to support the primer pump  16  and the check valve  33  on the hull side. 
     FIG. 9  illustrates yet another modification of the fuel supply devices described above. In  FIG. 9 , the same or similar members as or to the members described referring to  FIGS. 1–7  are assigned with the same reference numerals or symbols, and detailed descriptions of those members will not be repeated as appropriate. 
   The upstream side low pressure fuel supply conduit  26  of  FIG. 9  can include another check valve  64  positioned between the primary fuel supply system  17 , which can be formed with the primer pump  16  and the check valve  33 , and the low pressure fuel pump  14 . The check valve  64  only allows the fuel to flow to the outboard motor  1  side from the primary fuel supply system  17 . 
   Because of the construction in this embodiment, the check valve  64  can prevent the fuel from returning back to the main fuel tank  31  through the primer pump  16  from the outboard motor  1 . The primer pump  16  thus can be filled with the fuel all the time. Therefore, the primer pump  16  can transfer the fuel to the outboard motor  1  side at the same moment as the start of its operation. That is, the primer pump  16  can certainly transfer the fuel to the outboard motor  1  prior to the start of the engine  5 . 
   It is to be noted that the functions performed by the components of the engine control unit  34 , including the functions performed in any of the steps identified in the processes illustrated in  FIGS. 4–7 , and any data and/or maps used therewith can be referred to as “modules.” In the embodiments disclosed above, such modules can be in the form data tables or executable programs, routines or subroutines stored and/or run in the engine control unit  34 , or other devices. 
   It is to be noted that these modules, individually, collectively, or in various groupings, can be in the form of hard-wired feedback control circuits. Alternatively, these modules can be constructed of a dedicated processor and a memory for storing a computer program configured to perform the steps of the processes of  FIGS. 4–7  or other processes with reference to data tables or maps of other modules. Additionally, these modules can be constructed of a general purpose computer having a general purpose processor and the memory for storing a computer program for performing the steps of the processes of  FIGS. 4–7  or other processes with reference to data tables or maps of other modules. 
   Although these inventions have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. In addition, while several variations of the inventions have been shown and described in detail, other modifications, which are within the scope of these inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combination or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the inventions. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of at least some of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.