Gas tank vent valve
 

So when I take the cap off my car it hisses like it's not venting. Is it just the vent valve under the car. It also seems like it doesn't get quite enough fuel, could that be helping to cause that issue?

Re: Gas tank vent valve
 

That is normal. The tank retains some pressure as it vents through the charcoal canister. Which is controlled by a vapor pressure valve.

Unlike older cars our f-body's have a closed fuel system. Along with all (nearly all?) cars of this era.

As for not getting enough fuel, how can you tell? Fuel filter changed in recent months?

RBob.

Re: Gas tank vent valve
 

My '82 Recaro T/A was doing this and it turned out to be the purge solenoid for the charcoal canister was inop and stuck in the closed position.

Re: Gas tank vent valve
 

No it's never been changed, and I have the 2.8 mpfi and it just bogs all the time and in the morning especially it misfires horribly, and want's to die, idling real low than hmgets high again, didn't know if it was a fuel issue. Also my sending unit or fuel pump or whatever is pretty noisy, is that normal for these cars? Because in other Chevy I've been in, mainly the 2000s trucks when the pump is loud it means it's going out.