I have an 04 Grand Prix (not supercharged). I bought it and let it sit for about 6 months. Now the tank is hard to fill--the pump keeps shutting off. I asked a GM dealer about it. I thought it may have a roll over valve in the filler neck. The dealer said it does not but does have a purge valve that is probably stuck on top of the tank. Apparently it vents to the intake. Has anyone experienced this? I don't want to drop the tank without some confirmation that is the problem. I really don't know what else would cause pressure in the tank to keep kicking the gas pump off though.
Thanks.