1999 Alero will not take gas

About a week ago I tried to fill up the gas tank. The pump kept kicking off as if the tank was full. I thought maybe the problem was with the pump so I tried a different one. Got the same result.
When I got home I attemted to put gas in the tank using a gas can, it went in fine. I then drove back to the station and filled up with out any further problems.
Now the tank will not take gas again. Does anyone have any ideas what would cause this? Is there a screen in the fill neck? Is there a vent tube that may be clogged?

I had this problem with my old Grand Prix. The solution for me was simple. Instead of trying to pump the gas in as fast as it will go, set the trigger at about half way, or even a notch below full speed. Pumping it in slower should do it. I think the problem was that the fill neck couldn't handle that much gas and it was backing up, so the pump shut off thinking that the tank was full. But in all actuality, just the fill neck was full.

Thanks for the reply 1997GrandPrix but this is not the problem. I can actually fill the neck up with gas and it will hold it for a while before it drains into the tank. It acts as if the neck is clogged.

Proceed to beat your Alero into submission with a crow bar. That should teach it to clog up like that. haha

But in all seriousness I don't know, that was my only possible solution. I'm not exactly automobile-savvy. Hence the reason I'm on this board in the first place.

Hey grandprix thats funny LOL! Oldbills, there is a ball in the end of the filler neck about the size of a ping-pong ball that prevents people from siphoning gas out of the tank it may be stuck. I'm not sure if you can get to it without pulling the tank. Is the tank in center or rear? If you can get under the car look and see if you can see the fill hose. If you can pull it off the check valve may be in the line or it could be in the top of the tank at the hose connection. Good luck!!!