Apparatus and methods described herein provide for a spillover tank to extend the fuel capacity of the main wing tank of an aircraft. The spillover tank is located in the wing of the aircraft adjacent to the main wing tank. At least one aperture exists through the shared barrier between the main wing tank and the spillover tank that allows fuel to flow passively between the tanks. A scavenge pump mechanism driven by motive flow from the main fuel pumps continuously pumps fuel from the spillover tank into the main wing tank.