Sorry if this is the wrong place for this question. But I'm having an issue with filling my gas tank when I get to half a tank the gas pump will shut off and if I keep trying to fill it it shoots out of the filler neck which is annoying and embarrassing but very funny to your buddies in the car.
Anyway I crawled under the car and removed the vent valve and I was able to suck air and blow air through it. I also tried getting gas with it off and the problem persisted. I also made sure the gauge is working correctly by unplugging the sending unit and the gauge read empty then used a paperclip to see if the gauge read full which it did. Also If I let the gauge hit empty it is definitely empty learned that one quick.
Forgot to say it a 87 305 TPI Firebird
I can't really tell if it's a pressure problem it could be. Occasionally when I take the filler cap off I can hear pressure releasing but it's not often that it does that. If anyone has any pointers please let me know.

 

I have heard of that problem with aftermarket fuel tanks. The only solution I have read is to fill the tank very slowly, just barely depressing the fuel nozzle trigger.

Good luck,
Fred

 

is the vent line clear and moving air?

 

Anther item to check, is to see if the filler neck has been cut. Then patched with a piece of hose. Many of these tanks have a channel to allow air out of the tank, while fuel pours in. This is done via a piece of sheet metal mounted in the neck, like a two-tired bridge.

Open up the bridge between the tiers and all heck breaks loose.

RBob.