Just so you don't confuse things -- Diamonds is referring to the metal or plastic vent tube INSIDE the tank -- not the position in which it comes out through the stopper. The end of the vent tube should be situated at the top of the tank, but not quite touching it. Additionally, check to ensure that you fuel pick-up clunk isn't jamming against the back end of the tank (or the tube may be too stiff) & therefore not free to fall to the bottom. If it doesnt lie on the bottom of the tank, you won't get all of the available fuel.