Originally Posted by
onehundred80
There is a barrier that is on a float and it is supposed to help prevent over filling the gas up the filler tube and causing gas to enter the carbon filter. This barrier also prevents leekage from an overturned car. Unless the float is jammed open it should not happen too easily. Overfilling up the tube is a cause of the carbon filter filling with gasoline and setting a fault. If this float jams in the closed position it makes the gas tank very hard to fill. This is what I have gathered from previous posts and it makes sense to me.
I think the barrier stops the gas from going too high in the tank and going into the filter, the over filled gas in the filler tube will seep into the tank but not raise the level too high, keep filling the tube and the gas will get too high. It is this seeping that makes it possible to fill the tank when the barrier is jammed shut, it just takes a looooooooooong while.