Fuel tank closure with cap ejector spring

A fuel cap (10) for a filler neck (12) of a vehicle fuel system comprises an upper housing (18) and a lower housing (20), each of the upper and lower housing being adapted to be at least partially inserted into the filler neck (12) of a vehicle fuel system. The upper housing and lower housing are cooperatively configured to allow both rotational and axial relative movement with respect to one another. A seal (16) is located on the lower housing (20) and is configured to be sealingly engaged with the filler neck (12) when the fuel cap (10) is moved to a tightened position. A spring mount (22) is coupled to the upper housing (18) and a spring (24) engages the spring mount (22) and is positioned to assist in loosening the seal (16) from the filler neck (12) during removal of the fuel cap (10).