Fuel Temperature Sensor And Fuel Metering Valve

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

Fuel Temperature Sensor 

The fuel temperature sensor is located in a threaded port in the High Pressure (HP) fuel pump.

The sensor is a Negative Temperature Coefficient (NTC) sensor which is connected to the Powertrain Control Module (PCM) by two wires. The PCM fuel temperature sensor circuit consists of an internal voltage divider circuit which incorporates a NTC resistor. As the fuel temperature rises the resistance through the sensor decreases. The output from the sensor is the change in voltage as the NTC resistor allows more current to pass to ground relative to the temperature of the fuel.

The PCM monitors the fuel temperature constantly. If the fuel temperature exceeds 85°C (185°F), the PCM initiates an engine 'derate' strategy. This reduces the amount of fuel delivered to the fuel injectors in order to allow the fuel to cool. When this occurs, the driver may notice a loss of performance.

The wires to the fuel temperature sensor are monitored by the PCM for short and open circuit. The PCM also monitors the 5V supply. If a failure occurs a Diagnostic Trouble Code (DTC) is recorded in the PCM memory and the PCM uses a default fuel pressure value.

Fuel Metering Valve 

The fuel metering valve is located on the top of the High Pressure (HP) fuel pump. The valve is sealed to the HP fuel pump body with an O-ring seal and secured with two screws.

The fuel metering valve is a variable position solenoid operated valve that is controlled by the Powertrain Control Module (PCM) with a Pulse Width Modulation (PWM) signal.

The fuel metering valve controls the quantity of fuel delivered to the HP fuel pump from the fuel pump module in the fuel tank. The valve returns unwanted fuel back to the fuel tank. This avoids unused fuel being pressurized by the HP stage of the pump, only to be returned back to return system by the Fuel Rail Pressure (FRP) control valve. This would waste energy and heat the fuel.