Hello everyone, I have an '86 z28 and I have owned it for several years and have just dealt with this problem because nobody really knows how to fix it. The guy I bought the car off of had taken out the 305 and replaced it with a carb 350. However, he didn't do so hot of a job. The biggest issue I am having is I can't fill the gas tank up but half way then it starts coming up the filler neck (no matter how slow I pump gas). Then it over pressurizes like crazy while I'm driving it and after it's parked. He took off the charcoal canister and I'm wondering if I put one back on and vented it the way it was from the factory if it would fix all of this. I know there are tons of threads about this but nobody seems to have my exact problem. Thank y'all.

 

I had that problem on a 77 Monte Carlo, the tank vent should be on the drivers side of the engine bay, a hard medal line, I put a hose and a fuel water separator filter on mine and it fixed it.

 

Where would you get one of these fuel water seperator filters and how does that help the fuel tank pressurization?