Q-Jet Accelerator Pump Seal Problem

[Jim S.]

There is a posting by Lars over on the CF concerning Q-Jet accelerator pump seals that are being sold in rebuild kits. The concern is that the seal material is not compatible with modern alcohol blended gasoline fuels.

http://forums.corvetteforum.com/c3-t...t-quality.html

Jim

[Dan M.]

Re: Q-Jet Accelerator Pump Seal Problem

Thanks for the heads up Jim. As a 68 Q-jet owner, this affects me for sure. I am not certain of the source of the current seals in my accel pump but if the stumble symptoms start, I know the first place to inspect.

[Clem Z.]

Re: Q-Jet Accelerator Pump Seal Problem

i have been using hy grade rebuild kits with the blue,viton, pump cup with no problems for years. from the pictures it looks to me that projections on the plastic part of the pump that holds the pump cup in place do not look like they are as long as the original GM pumps. when putting the pump cup on the original GM pumps you need a special fixture to stretch it over the projections because they stick out so far. if you use any of these "octane boosters" you will have pump cup problems no matter whose kit you use

[Frederick W.]

Re: Q-Jet Accelerator Pump Seal Problem

That's my carb, for my 68. Lars has it now at his shop in Colorado.

When I bought the car, in the fall of last year, it had a problem with the accel pump. I replaced the pump with a Napa/echlin part. It lasted a few days then started crapping out.
I sent it to Lars, since he kindly agreed to rebuild it for me. When he shipped it back, it was great for a day or so, then accel pump crapped out. I contacted Lars and he shipped me another pump. I put it in, and it was great for a day, then crapped out.
Lars asked me to send the carb back, which I did. He looked at it yesterday, and the pictures show the problem.
All of these pumps were advertised as being compatible with modern fuels and "methanol resistant". Um, what about ethanol?

Fred

[Clem Z.]

Re: Q-Jet Accelerator Pump Seal Problem

i posted my opinion above and if get time i will post a picture of a GM pump to show what that the projections should look like.

[Frederick W.]

Re: Q-Jet Accelerator Pump Seal Problem

i posted my opinion above and if get time i will post a picture of a GM pump to show what that the projections should look like.

Thanks Clem,

I did notice that putting the pump cup over those little projections didn't take much stretching, and it was kinda loose after it was on. This may be the problem. I'm sure Lars with give a full analysis of his take on it.

Fred

[Clem Z.]

Re: Q-Jet Accelerator Pump Seal Problem

here you go !

[Clem Z.]

Re: Q-Jet Accelerator Pump Seal Problem

i guess that guy over on the CF does not believe me because i have rebuilt lots of Q jets using the blue pump cup with no come backs.

[Joseph K.]

Re: Q-Jet Accelerator Pump Seal Problem

I agee with clem. I installed a black pump in a Q-Jet and witin in two days it did not work. I then installed the blue one and it is still working fine. Our carb rebuilder in Middlesex, NJ also confired this. BTW I used him for parts, he knew his stuff, and does great work.

[Frederick W.]

Re: Q-Jet Accelerator Pump Seal Problem

I agee with clem. I installed a black pump in a Q-Jet and witin in two days it did not work. I then installed the blue one and it is still working fine. Our carb rebuilder in Middlesex, NJ also confired this. BTW I used him for parts, he knew his stuff, and does great work.

I used 3 different Echlin blue pumps and they all seized up within hours.

The tests that Lars has done show that the blue pumps are swelling in the fuel and becoming soft. This is a direct observation after soaking them in pump gas for a couple of hours. When he then tests them in the pump bore, they seize just as has been happening to me.

It's either a problem with our fuel here in the region or a problem with the pumps from Echlin. Apparently Echlin merged product lines with Standard/Hygrade in the recent past. It may have something to do with that.

Hopefully, Lars will find a good pump to put in my carb.

Fred

[Clem Z.]

Re: Q-Jet Accelerator Pump Seal Problem

I used 3 different Echlin blue pumps and they all seized up within hours.

The tests that Lars has done show that the blue pumps are swelling in the fuel and becoming soft. This is a direct observation after soaking them in pump gas for a couple of hours. When he then tests them in the pump bore, they seize just as has been happening to me.

It's either a problem with our fuel here in the region or a problem with the pumps from Echlin. Apparently Echlin merged product lines with Standard/Hygrade in the recent past. It may have something to do with that.

Hopefully, Lars will find a good pump to put in my carb.

Fred

i have been using nothing but hygrade carb kits and i have not had a comeback since they have switched to ethanol here in western Pa. about 10 years ago.

[Joseph K.]

Re: Q-Jet Accelerator Pump Seal Problem

I don't know if this helps....there are parts of the article that should be skipped but at the end they give some compatible materials that could be used. The question is the material that we are buying compatible with the new fuel???

http://running_on_alcohol.tripod.com/id32.html