P.1 

OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

190) IV-C-157 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:21:01 AM Sheet 190 of 232 
P.2 

^-"•l- i 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

ANN ARBOR, MICHIGAN 48105 

-EB I 5 !989 

Mr. James E. Pasek, Manager 

Automotive Emission Control 

Environmental Activities Staff 

General Motors Technical Center 

30400 Mound Road 

Warren, MI 48090-9015 

,S>^ 

^ OFFICE OF 

•fp AIR AND RADIATION 

e* --# 

^ i> 

Dear Mr. Pasek 

response 

;on, 

I am writing in to your 

to Mr. Richard wil 

Sources. In that letter 

issues related to the 

proposed new evaporative, 

procedures. This letter 

positions on the issues you raised, 

point out that our final positions 

December 2, 1989 letter 

Director of the Office of Mobile 

you requested clarification of some 

Environmental Protection Agency's 

exhaust and refueling emissions test 

is intended to provide our current 

However, I would like to 

will be determined only 

after we have fully reviewed all comments received in response 

to the onboard refueling Supplemental Notice of Proposed 

Rulemaking (SNPRM). 

The first issue which you requested clarification on was 

that of the "engineering review" of vehicle designs in the 

proposed section 86.XXX-8(e). The purpose of this requirement 

is to guarantee that all vapors generated in the fuel tank are 

vented only to the engine or canister and never directly to the 

atmosphere. The only exception to this would be to al^ow for 

venting in the case of an emergency (i.e., crimped vapor line, 

etc.). We view the implementation of this requirement as being 

similar to that of the engine crankcase ventilation 

requirements and feel that it will be fairly straightforward to 

establish compliance with the requirement based on such things 

as component sizing. We will be requesting comments 

specifically on how we may improve or clarify it in the SNPRM. 
The second issue you raised concerned the cap removal 

procedure at the start of the hot soak test. Your 

understanding of our current position on the use of inner seals 

on onboard system tank vent valve assemblies (TWA) as stated 

in your letter is correct. However, as with all test 

procedure-related issues, our final position will be developed 

only after the review of all comments received in response to 

the SNPRM. 

In your letter you asked whether we would consider 

implementation of the proposed section 86.138-XX prior to, or 

in the absence of, an onboard requirement. We feel that our 

intent to do this was made clear at the June 30, 1988 workshop 

and I would like to reaffirm that position now. You also asked 

whether overriding the inner seal on a TWA would be acceptable 

during cap-off vehicle storage periods to prevent unwanted 

canister loading. We have not developed a position on this 

issue at the present. However, if you feel that there is a 

need to allow seal overriding we would ask that you provide an 

appropriate justification. 

Finally, you referenced an October 14, 1988 letter to Mr. 

Wilson in which Mr. Sam Leonard urged the EPA staff to make 

more time available to address other test procedure-related 

issues. A meeting to discuss many of General Motor's concerns 

was held on January 5, 1989 between members of your staff and 

mine. At that time we reviewed a detailed list of test 

procedure questions provided by GM. We feel that we have been 

responsive to your concerns thus far and will continue to be as 

the need arises. 

Sincerely yours, 

L-eftaries L. -dray^'Vjr. 

Director 

Emission Control Technology Division 

cc: DocK:eo!s.:A-87-ll$ 

6764W