When I remove the fuel cap to fuel up there is a large release of pressure from the tank. Is there any issues to worry about? Does this effect the cars performance? Please move if this is the wrong spot for this.

 

Entirely normal.

 

I have observed that the lower the fuel level and/or the hotter it is out, the more you hear it hiss when you remove the cap.

 

Isnt it only normal if it isnt excessive? I read that if the pressure release is out of control it could be a bad evaporative emmision pressure control valve. Ive been reading up on this because the pressure is so bad in my tank I am waiting for the tank to explode. The vapors are so bad that it burns my eyes and I have to step away from the car for about 30 seconds till they are all released.

 

I assume there is a pressure release valve somewhere if it get dangerously high. Mine just has a 2 seconds whoosh sound when its hot and low on gas.

 

I am having the same problem with excessive pressure in the fuel tank. I worry about parking it in the garage with the natural gas powered water heater waiting to light the fumes!

Last month I replaced the charcoal cannister, blew out the lines and changed the vacuum switch (#12555984). Reset "check engine" light and passed smog. (-: Opened a good bottle of wine to celebrate! However now I have this pressure like the gas is boiling in the tank. I noticed this yesterday and yes it was 100 degrees out but I have never had this problem before. Should I change the Evap Solenoid (#1997201)? The fuel pump is stock.

 

If you had any crap in the lines at all when you blew them out, then yes, change out the EVAP solenoid. I had the charcoal canister on my '95 Z28 'vert go bad and it filled the evap lines with charcoal. I blew them all out and replaced the canister, vacuum switch and EVAP solenoid and all is well.

Just make sure ALL the lines going to the solenoid are clear (especially the small one that snakes under the throttlebody), otherwise you will just clog up the new solenoid.

 

Yes there is a pressure relief valve. It's located behind the driver's side rear axle.

 

That is NOT a pressure relief valve. It is a vacuum displacement valve, ie, it lets air in when vacuum is present. It holds against and allows pressure.

It is there to make sure as you deplete the gas air can get in, but fuel vapors cannot get out from there. That is what the EVAP system is for.

 

Per my 1995 Service Manual:

"The fuel tank vent valve, located in the rear of the vehicle by the fuel tank, is a pressure/vacuum relief valve. When fuel tank pressure exceeds a specified pressure the valve will open allowing tank pressure to bleed off. When the fuel tank is in a vacuum condition, the vent valve will open when the vacuum is within a specified range allowing fresh are to be pulled in."