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OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

199) IV-C-166 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:21:02 AM Sheet 199 of 232 
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

ANN ARBOR. MICHIGAN 48105 

X7 -6 - / ^ 

MAY 2 4 l98 9 OFFICE OF 

AIR AND RADIATION 

Mr. James E. Pasek 

Manager, Federal Activities 

Automotive Emission Control 

General Motors Corp. 

General Motors Technical Center 

30400 Mound Rd. 

Warren, MI 48090-9015 

Dear Mr. Pasek: 

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pPA AIR DOCKET 

This is in response to your letter of March 9, 1989, in 

which you commented upon several areas relating to onboard 

refueling emissions controls, and testing performed by EPA to 

evaluate prototype control systems and test procedures. I wish 

to respond to several of the points raised in your letter, and 

to inform you of current EPA activities in this area. 

A number of your comments focus on EPA testing of two 

Exxon-prepared vehicles equipped with onboard refueling 

controls. In my previous communications with you, I outlined 

the intended scope of these tests, and EPA's position that the 

two test vehicles were substantially different than EPA's 

simplified refueling control system, regardless of what 

incentives Exxon may have, had to build systems "that would 

function effectively." Because these vehicles were clearly 

deficient even in terms .of meeting our proposed emissions 

standard, we saw no basis for any more detailed evaluation of 

either vehicle. 

During the period since my January 17, 1989 letter to you, 

EPA has continued a development and testing program that 

focuses on your concern that our simplified liquid seal based 

concept is not applicable to production vehicles. We have 

recently completed installation and testing of onboard controls 

on a Ford Taurus vehicle. Our testing, which has included both 

laboratory and in-use evaluations, has shown that performance 

of the onboard-equipped vehicle meets or exceeds stock vehicle 

performance. We have successfully tested the vehicle for 

fillability at fuel dispensing rates in excess of 15 gallons 

per minute, and at fuel temperatures approaching 100°F. 

Incidentally, late model GM vehicles which we have tested at 

these severe conditions are frequently unable to be refueled at 

all. Tests carried out under our full proposed refueling test 

procedure have shown compliance v/ith our proposed standards and 

no impacts of the refueling emissions controls on exhaust 
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emissions. We will be making a briefing in the near future on 

the vehicle development and evaluation results that are 

available. 

I also wish to respond to two other areas of concern 

raised in you letter. The first of these is the ability of 

onboard-equipped vehicles to control running loss emissions. 

This source of emissions is, of course, of great interest to 

EPA. As you know, we are preparing a proposal for improved 

evaporative and running loss controls. As we have indicated in 

previous communications v/ith you, we believe that, coupled v/ith 

our volatility proposal, running losses can be controlled 

without the need for pressurized fuel tanks and the apparent 

safety risks associated with such an approach. 

The second area that I wish to respond to concerns the 

canister conditioning and loading procedure associated with 

refueling test procedures. I must reiterate the EPA view that 

onboard vehicles should be capable of passing the refueling 

test regardless of canister loading or history at the start of 

the test. The proposed canister conditioning procedure is 

intended to specify only a minimum canister loading at the 

start of a test, rather than to specify a narrow range of 

canister loadings between carefully controlled upper and lower 

bounds. It is the intent of EPA that refueling control systems 

be sufficiently robust to be insensitive to initial canister 

loadings that are above the specified minimum load. 

Variability that is inherent in any test procedure, including 

the proposed refueling test procedure, is far less than the 

real-world variability that an in-use system will be subjected 

to. Any refueling emissions control system that is 

sufficiently sensitive to canister conditioning or history that 

it is likely to fail refueling tests due to variability in the 

canister conditioning procedure is unlikely to attain the level 

of in-use control intended by EPA. 

Finally, I would like to inquire about the status of an 

understanding originating in a meeting with Mr. Stempel of GM 

with EPA Administrator Lee Thomas on December 13, 1988. One 

outcome of that meeting was a commitment by GM that we would 

receive a comprehensive briefing on your technical and safety 

concerns. We will look forward to hearing from you about this 

matter. 

Sincerely yours, 

'Ut<J 

Dr. David B. Bartus, Chemical Engineer 

Standards Development and Support Branch 

cc: Docket A-87-11 

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