99 Astro fuel shoots back out when filling

99 Astro Van Passenger 133,000 miles Vortec v6 Fuel gauge stopped working and now fuel blows back when trying to fill. Got engine codes po452 and 453 Hard to start after sitting for more than a day. Runs rough over first gear. I was told there is a valve that is supposed to open when engine is off to let air out so fuel can come in. Where do i start?

You were told wrong. There is no "vent valve" in the fuel system to allow air to escape when filling. There is a vent hose from the left side of the tank to the filler neck about three inches below the opening, but no "vent valve" which opens and closes for filling.

There is, however, an anti-surge/anti-siphon valve on the lower end of the fill tube, and it looks exactly like this:

http://www.wwdsltd.com/files/FuelFillTube.jpg

That can interfere with fuel filling if it has been damaged by someone attempting to siphon fuel or in an accident.

Thank you for your reply! I was starting to give up hope on this forum. Do you think the anti-siphon valve could be stuck shut? How do I replace? The error codes I'm getting are po452 and 3 which I think have to do with fuel tank pressure. The van will not start at all today (It is VERY humid) any suggestions would be greatly appreciated..