F 150 Super Crew 4WD V8-5.4L Prop SOHC VIN Z (2003)
Fuel Pressure Sensor: Description and Operation
Fuel Absolute Pressure Sensor
The fuel absolute pressure (FAP) sensor is integral to the compuvalve. It is a pressure transducer that converts pressure to voltage through a
piezo-resistive element. This signal is monitored to make sure that the pressure regulator is functioning properly and is used to adjust the injector
combination according to supply pressure. The FAP sensor allows the vehicle to start in ALT fuel mode at a minimum of 25 psia. It also controls
when the vehicle will auto switch to gasoline (25 psia).
