Fuel Absolute Pressure Sensor (CNG & LPG)
WARNING: This page is about a different car, the 2002 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The Fuel Absolute Pressure (FAP) sensor is integral to compuvalve. FAP sensor is a pressure transducer that converts pressure to voltage through a piezo-resistive element. FAP voltage signal is monitored to ensure that gas regulator is operating correctly. FAP sensor is used to adjust which injector combination is used. FAP sensor allows vehicle to start in ALT fuel mode at a minimum of 95 psi (6.7 kg/cm2 ) for CNG, or a minimum of 24.6 psi (1.73 kg/cm2 ) for LPG. When CNG pressure is at 68.8 psi (4.84 kg/cm2 ), or LPG pressure is at 24.6 psi (1.73 kg/cm2 ), FAP sensor sends a signal to AFCM and compuvalve, and bi-fuel system will automatically switch from ALT mode to GAS mode. For additional bi-fuel switch over specifications, see Fig 1.