Seville STS V8-4.6L VIN 9 (1998)
Fuel Tank Pressure Sensor: Description and Operation
Circuit Description
The fuel tank pressure sensor is used to detect small leaks in the evaporative emission system. The fuel tank pressure sensor is a three wire strain gauge
sensor much like that of the common GM MAP sensor. However, this sensor has very different electrical characteristics due to its pressure differential
design. The sensor measures the difference between the air pressure (or vacuum) in the fuel tank and the outside air pressure. The sensor mounts at the
top of the fuel tank. A three wire electrical harness connects it to the Powertrain Control Module (PCM). The PCM supplies a five volt reference voltage
and ground to the sensor. The sensor will return a voltage between 0.1 and 4.9 volts. When the air pressure in the fuel tank is equal to the outside air
pressure, such as when the fuel fill cap is removed, the output voltage of the sensor will be 1.3 to 1.7 volts. Refer to EVAP Control System Diagnosis.
See: Emission Control Systems/Evaporative Emissions System/Testing and Inspection
