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OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

193) IV-C-160 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:21:01 AM Sheet 193 of 232 
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~ \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

w '«•. P*^y 5 

ANN ARBOR. MICHIGAN 48105 

OFFICE OF 

AIR AND RADIATION 

APR I 2 !989 

Mr. George Parker 

Associate Administrator for Enforcement 

National Highway Traffic Safety Administration 

400 Seventh Street, SW 

Washington, DC 20590 

Dear Mr. Parker: 

This letter is in response to your request for more 

information about the results of our onboard vehicle 

development project. We believe we have been quite successful 

in applying our simplified onboard refueling concept to a Ford 

Taurus vehicle. The following paragraphs will briefly 

summarize our approach and the results we have obtained. All 

of this material will be covered in more depth during the 

briefings we have suggested for you and your staff. 

As you know, EPA has previously applied simplified onboard 

refueling controls to the fuel systems of late model General 

Motors and Ford products. We demonstrated our system on a GM 

Cutlass Ciera fuel tank in the Spring of 1988 and on a Ford 

Taurus fuel tank in the Fall of 1988. Both of these systems 

performed as we had desired. They eliminated spitback, met our 

proposed refueling emission standard and had excellent 

fillability for conditions meeting the volatility and 

dispensing rate limits which EPA had proposed. However, both 

GM and Ford subsequently claimed that this system did not work 

when installed on production vehicles. API had also built 

prototype vehicles using concepts similar to ours, which 

experienced both performance and emissions problems in NHTSA 

and EPA testing. In response to these developments, and to 

deal with objections that the EPA system demonstrations had not 

dealt with vehicle purge controls, we decided to evaluate the 

potential for a vehicle-based system. 

Our biggest concern stemmed from the fact that we were not 

in a position to be able to significantly modify any vehicle's 

purge control strategy. To increase overall purge amounts 

without affecting emissions or driveability could require 

modifications to purge strategy as well as purge flow rates. 

Because these functions are controlled by the vehicle's 

computer, we were not in a position to easily make 

modifications. Therefore, our desire was to determine if there 
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were any current production vehicles which might already have 

sufficient purge to handle an onboard system. Based upon 

screening of our running loss test data and some subsequent 

in-house evaluations, we identified the Ford Taurus as 

apparently having sufficient purge for an onboard canister. A 

Taurus was therefore selected for evaluation. 

We faced a further obstacle in that current in-use 

conditions for both fuel dispensing rates and volatility exceed 

those limits which we had proposed to accompany onboard 

controls. However, we felt it important that any vehicle which 

we might develop be able to perform satisfactorily for current 

as well as future conditions. This meant that improvements 

would have to be made to our original design to increase its 

ability to perform under adverse in-use conditions. We felt 

that improvements would be needed in three key areas: reduced 

flow resistance for the liquid seal and reduced pressure losses 

from both the anti-spitback valve and the rollover/vent valve. 

We have made the needed improvements by changing the liquid 

seal device from a narrowed section of the fillpipe to an 

"overflow" tube, and by improving the anti-spitback and 

rollover/vent valves. Overall, the system remains the same in 

basic concept and operation as our earlier versions. 

The system as we now have it installed on the Taurus 

vehicle has been put through an extensive amount of testing. 

"The rollover/vent valve itself has been rollover tested on a 

fuel tank using the rotation rates of FMVSS 301, with zero 

leakage for either left or right rollovers. Refueling 

emissions when measured on the full proposed EPA test procedure 

are very low, similar to our previous hardware. There are no 

discernible effects of the refueling system on exhaust or 

evaporative emissions, and driveability appears not to be 

affected. We have made no modifications to the stock purge 

system. 

Our most intensive testing and development work has been 

directed at fillability evaluations. In our laboratory testing 

we have simulated conditions far more challenging than any 

found in-use, with flow rates up to 15.1 gallons per minute 

(the limit of our dispensing equipment) and fuel RVP of 14-15 

psi. In this testing, the onboard car has no spitback. 

Back-to-back tests of a stock Taurus generated some fuel 

droplet spray during filling and some spitback at the end of 

the fill. Other late model domestic cars were generally either 

unable to fill at these conditions, or produced frequent 

premature shutoffs and large amounts of spitback. We have also 

done a substantial amount of testing at local service 

stations. We have found 14-15 psi RVP fuel, high springtime 

temperatures and dispensing fates over 12 gallons per minute. 
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The onboard and stock car are comparable in their ability to 

fill under such conditions with little or no spitback. We 

found other stock vehicles to have significant problems with 

spitback and premature shutoff for these conditions. 

In summary, we believe we have successfully adapted our 

simplified refueling hardware concept to the Taurus. It meets 

all current and proposed emission standards, while at the same 

time maintaining other vehicle performance characteristics. We 

look forward to the opportunity to provide you a first hand 

briefing on the results of our work and to show you our car. 

Sincerely yours, 

X 

Charles L. Gray/v/r. 

Director' 

Emission Control Technology Division 

cc: Barry Felrice, NHTSA 

7018W