Rodeo S 2WD L4-2.2L (1999)
Fuel Tank Pressure Sensor: Description and Operation
Fuel Tank Pressure Sensor
The fuel tank pressure sensor is a three-wire strain gauge sensor similar to a common MAP sensor. However, the fuel tank pressure 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 pump assembly. A three-wire electrical harness connects it to the PCM. The PCM supplies a five-volt reference
voltage and a 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 cap is removed, the output voltage of the sensor will be 1.3 to 1.7 volts.
When the air pressure in the fuel tank is 4.5 in. H20 (1.25 kpa), the sensor output voltage will be 0.5 ± 0.2 V. When there is neither vacuum nor pressure
in the fuel tank, the sensor voltage will be 1.5 V. At -14 in. H20 (-3.75 kpa), the sensor voltage will be 4.5 ± 1-0.2 V.
