Hello,
I'm posting to see if someone can help me diagnose a problem with my 86 camaro z28 305 carb, 5spd manual.

When I got the car 2 weeks ago it had a fuel pump leak, I installed a new fuel pump this past weekend to fix the leak and put a new cap on the gas tank because it was building up pressure in the tank, you could hear it release the pressure when you take the cap off like as if you were opening a soda bottle.

I thought the new cap would take care of the problem but it did not. I'm worried that this pressure build up is just going to cause the fuel pump to spring a leak again due to built up pressure. I'm trying to find out where it is supposed to vent the pressure if it's not out the cap, and what steps I can take to correct the problem.

Thanks!

 

You can buy a vented cap, but sometimes pressure will still build. There is also a vent under the car just above the gas tank - if you crawl under you can see it.

I don't think any pressure built up would do anything to a fuel pump though - the pressure was tremendous in my 1992 RS TBI before I swapped to carb and got rid of the evap canister - but even after that, I still get pressure on occasion - especially on days where the temps are over 90.

 

I've had my car since new. It hisses more air when removing the gas cap than any car I've ever driven. This is normal. The hissing is more pronounced in the hot summer months. But even when it's cool out, it still lets a bunch of air out. I'm using the original sealed gas cap.

 

It could possibly be the canister purge valve(solenoid) if they don't operate properly they can cause pressure to build up. It happened on my 99ta,different car yes,but the system works the same.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Canister-Purge-Valve-BWD_5011027-P_760_R|GRPEMISAMS_1160853538___#