(06 October 2015 - 03:27 PM) I am getting a Huge amount of pressure buildup in the fuel tank of my 92 Trans AM. It also has lost pedal response after an hour or so of city driving. It will idle, but won't rev at all. After I pop the fuel cap it is OK. The EGR valve & canister are new. Any suggestions? The dealer is stumped.

 

There is supposed to be SOME pressure allowed in the tank (enough to give a good hiss when the crack the cap open on a warm day). Sounds like yours is getting out of hand, though.

There is a pressure/vacuum relief valve back by the tank that serves essentially the same purpose as the vented gas cap that most cars have. If that's plugged up or otherwise malfunctioning some odd stuff can happen.

I am not sure if those valves are available any more (perhaps somebody could chime in on that). Worst case, buy a vented gas cap that fits the car (the stock one is non-vented). They aren't easy to come by either, apparently, but here's a thread about them:

https://www.thirdgen.org/forums/afte...ented-gas.html

 

Remove the gas cap, unhook the gas tank vent hose at the canister, blow some compressed air (don't go crazy here) into the hose & have a helper listen at the tank.

 

Thanks Damon- That was the problem. It is in the tank so a little more costly to fix. At least it has been identified.