A permanent closure for fuel tanks mounted to an access door (28) with a hinge (30) connected to a vehicle, having an extended housing (22) which contains a rubber gasket (14) on the interior base, a spring (16) and a slideable internal fuel cap (24) Which meets EPA specifications. When the hinged access door (28) is in a closed position, a filler tube (20) on the vehicle enters a hole (10) in the extended housing (22) which meets the internal fuel cap (24) and an o-ring (12). A seal is obtained by closing the hinged access door (28) which presses the internal fuel cap (24) and the o-ring (12) against the filler tube (20), and into the rubber gasket (14) at the interior base of the extended housing (22). A locking pin (26), contacting a notch in the extended housing (22), insures the access door (28) remains closed, thus providing a continuous seal, and when released by a latch in the passenger compartment, maintains a seal, yet the spring partially urges the hinged access door (28) open. Vent holes (18) provide proper ventilation. The access door (28) is then easily opened exposing the filler tube (20) for refueling.