Greetings from across the pond. I hope this is in the correct section of the board, but there isn't a specific fuel-related area (not counting carb or injection sections!)

I filled my '85 Firebird up with fuel until the pump clicked off. I've only had the car a few days so this was the first time. Actually I've had the car a few weeks, but the local garage (repair shop) had her most of that time whilst they repaired the stress cracks near the steering box

Anyway, off I go down the road, full tank of gas, the Holley happily gulping it down rather quickly When I took the first long right hand bend I noticed a wet trail from the left side of the car.... This I can do without!! Whilst crappy gas mileage was not an issue when I bought my toy (I have a sensible car to go to work), I do expect the gas to go through the engine
Upon inspecting the filler cap (aluminium, screw-on-until-it-clicks-type) I found that the area inside the middle of the cap had a hole roughly punched in it. So, the fuel was sloshing up the pipe, straight through the cap and out. The rubber seal on the cap was in good condition, but wasn't doing anything.
I repaired this rough hole with some epoxy resin. I figured that the tank would vent via the evaporative emission control canister thingy under the hood. Not the case it seems. After going for a short drive I undid the cap and was met by much hissing and releasing of fumes; the tank had been pressurised rather than being sucked in as the fuel was used.

Sorry for the essay, but I thought I 'd give as much detail as possible. So, the question is should the filler cap have some sort of vent in it or is there a breather pipe for the tank elsewhere?

Cheers,
Mark.

 

Actually mine has pressure too, I thought that was normal. Any insight anyone?

 

Yes, pressure is normal.

If your gas cap has been sodomized, get a new one.

Unfortunately, the stress cracks are normal too; an "undocumented feature", to quote a famous software mfr.

 

Thanks guys

Mark.

 

Yeah thanks