Fuel Low Pressure Sensor

Fuel Low Pressure Sensor

Fuel low pressure sensor
The fuel low pressure sensor is bolted into the fuel feed line between the two high-pressure pumps.
The fuel low pressure sensor is used to measure the fuel pressure in the delivery line. The fuel is supplied by the fuel pump in line with requirements.
The purpose of the fuel low pressure sensor is to assist in electric fuel pump activation (EKPS). The engine management system evaluates the analogue output signal.

Functional description
Expansion measurement strips are used to detect the pressure.
The pressure applied deforms a steel membrane in the sensor that is fitted with expansion measurement strips. The changes in resistance in the expansion measurement strips are detected electronically by a measurement bridge and evaluated. The measured voltage is then included as an actual value in the electric fuel pump activation.







Structure and inner circuit
The fuel low pressure sensor is connected by means of a 3-pin plug-in connection.
The sensor is supplied with 5 Volts by the engine management system.







Characteristic curve and target values
The fuel pressure information is sent to the engine management system across a signal line.
The signal for the fuel pressure, which can be evaluated, fluctuates depending on the pressure. The measuring range of approx. 0.5 to 4.5 Volts corresponds to a fuel pressure of 0.1 kPa (1 bar) to 1.1 kPa (11 bar).







Observe the following target values for the fuel low pressure sensor:

Variable Value
Voltage range for fuel low pressure 0.5 to 4.5 Volts
sensor
Measuring range for fuel delivery 1 to 11 bar
pressure
Maximum output current 8 mA
Temperature range -40 °C to 140 °C

Diagnosis instructions

Failure of the component
If the fuel low pressure sensor fails, the following behavior is to be expected:
- Fault code memory entry in the engine control unit
- Emergency operation with substitute value

General information
Diagnosis of the fuel low pressure sensor is started as soon as the ignition is switched on. Subsequently, the diagnosis runs continuously every 100 ms.

No liability can be accepted for printing or other errors. Subject to changes of a technical nature