AirSensors fuel injection systems commonly used electric fuel pumps manufactured by Walbro. They were designed for either in-tank or in-line mounting, with inlets of 1/2" (12mm) and outlets of 3/8". Models 5530 and 532 were the most common; however, both models are no longer in production. Running at system pressures of nominally 39 psi or 55 psi, they were designed to provide fuel flow adequate for the horsepower ratings of the engines they fed, measured in gallons per hour. Several fuel pumps commonly available today from different manufacturers can replace the Walbro, if the demands of the engine are satisfied.