I am having trouble filling the gas tank on my 2003 Ford Taurus. The nozzle keeps shutting off because the gas is backing up in the fuel filler neck pipe. Even if I go slow, it will still back up. Any help what might be causing this?

 

There is a vent valve on the tank that may be faulty. Or possibly the vent tube beside the fill neck is plugged. But something is stopping the air from getting out when the fuel is going in. That is why you have trouble with it shutting off.