Fuel Pressure Sensor: Description and Operation

Bi-Fuel/Alternative Fuels

FUEL PRESSURE SENSOR (FPS)

The FPS is a pressure transducer. The AF ECU supplies about 5 volts on the FPS reference circuit. The AF ECU also supplies a signal and ground circuit to the FPS. Located at the end of the fuel tank, threaded into the HPL, the FPS supplies a voltage signal to the AF ECU. With a full fuel tank (high pressure) a high voltage signal will be monitored by the AF ECU. The volume of CNG varies with temperature and pressure. This will vary the amount of fuel vs. the signal voltage the FPS supplies to the AF ECU. In order to compensate for the different voltage factors, a tank mounted (internal) Fuel Temperature Sensor (FTS) is also monitored by the AF ECU. The AF ECU performs a calculation on the FPS voltage vs. the in-tank temperature. The AF ECU will then control the fuel gauge to display the correct fuel level.