Bad Gas Tank Gaskets

[Rick Norwood]

This is my first attempt at posting Photographs to the Forum so please bear with me. I'll keep trying to get some better pic's and edit them in.

I recently had to replace the fuel pump on my 93 S-10 Blazer 4.3L 2WD. I bought a Bosch Fuel Pump kit from Autozone for $100 USD. Everything seemed to go fine until I tried to take the Truck through Emissions Testing. In Arizona, the emissions test includes a pressure test of the Fuel tank and the gas cap. well, my fuel tank failed to hold the required 10 pound pressure test. Here's why.




Here is a picture of two gaskets, the one on the left is a simple O-ring that came in the Bosch Kit. The one on the right I bought from a GM Dealer after the fact. The GM Gasket also has 3 metal locating tabs that help to hold the gasket in place during installation. The GM part number is 22515965.

I used a micrometer and measured both gaskets and I could not believe what I found. The Bosch Gasket measured .220 thick (or 7/32 inch) while the GM Gasket measured .254 thick (or 1/4 inch). The difference of .034 or 1/32 inch. I initially installed the Bosch O-Ring that came with the kit and never really gave it a second thought. This thinner gasket resulted in my having to drop the tank again and replace the gasket in order to pass emissions. In addition, the Bosch O-ring gasket is also slightly larger in overall diameter, Which could cause the Gasket to not fit into the tank groove properly. In both measurements, the Bosch gasket was clearly not the correct replacement gasket. The reduced "Pinch" of the thinner gasket did me in.

Once the new gasket was replaced, the truck passed emissions with no trouble what so ever.

I do want to say in all fairness, the Bosch gasket never seemed to leak any gasoline that I could see. But if you find yourself in need of a fuel pump, do yourself a favor and pick up a GM gasket from the dealer. Mine only cost $10 USD. That 10 bucks could save you 2 hours of needless labor of having to R&R your tank. If you do buy a GM Gasket and find that you don't need it, Don't open the bag and the dealer should take it back.

[OverBoardProject]

Bosch is a pretty good company, and that's a ligit complaint.

If you contact them they'll probably fix the problem for future buyers, and I wouldn't be suprised if they send you some coin to cover your costs anyways.

http://www.boschusa.com/ContactUs/AutoPartsFAQs/

Can you let us know what their response is?

Thanks