Fuel Tank Pressure Sensor

The fuel tank pressure sensor is similar to the Manifold Absolute Pressure (MAP) sensor. The sensor is used to measure the difference between the air pressure, or vacuum, in the fuel tank and the outside air pressure. The PCM supplies a 5 volt reference and a ground to the sensor and the sensor sends a voltage signal between 0.1 and 4.9 volts back to the PCM. When the air pressure in the fuel tank is equal to the outside air pressure, as when the fuel cap is removed, the output voltage of the sensor will be from 1.3 to 1.7 volts.