Fuel Tank on 2000 Ford Taurus

What could the problem be if when I try to put gas in the gas tank it acts as though the tank is full and spits the gas back out at me or clicks the nozzle off as it does when the tank is full? My gas gauge is broken but I know I need gas, I have even run out of gas after just trying to put gas in and stopping because it spits it back at me as though it is full.

Asked by for the 2000 Ford Taurus
This can be caused by a few things. There is a rollover valve in your filler neck that could be malfunctioning. There is also vent pipe that could be closed off for some reason. It could even be that your vapor canister is saturated. Do you ever 'top off' your tank after the first 'click; when filling?

OK, thank you for you honesty. This is not recommended because the carbon canister will get saturated and then can plug up and cause 'spit back' when filling up the vehicle. Do you ever have any Check Engine or Service Engine Soon lights come on? I ask this because if you do, it could be from a fault in your evaporative system which could help you pin point which part of your fuel tank system is having a problem. If so, you can have the code retrieved by a good tech for 1/2 of labor. I can help with the interpretation. Parts Stores mean well, but are not really qualified. They MAY, unintentionally ,head you in the wrong direction.
Yes dandd, I do top off sometimes after the first click.