Fuel Tank Pressure Sensor - 3

The fuel tank pressure sensor (1) is mounted on top of the modular fuel sender. The sensor measures the difference between the fuel vapor pressure (or vacuum) in the fuel tank and the outside air pressure. A three wire electrical harness connects it to the Powertrain Control Module (PCM). The PCM supplies a 5 volt reference signal and a ground to the sensor. The sensor returns a voltage between 0.1 volts - 4.9 volts back to the PCM, depending on the fuel vapor pressure in the fuel tank. When the fuel pressure in the tank is equal to the outside air pressure, such as when the fuel cap is removed, the sensor output voltage will be between 1.3-1.7 volts.