Fuel Pump Control

Fuel Pump Control







The following components are included in the system which controls the fuel pump:
- Engine control module (ECM) with built-in atmospheric pressure sensor
- Fuel pressure sensor
- Control module for the fuel pump (FP) (Pump Electronic Module).

Function
A piezo-electric fuel pressure sensor transmits a voltage signal to the engine control module (ECM) about the actual pressure in the fuel rail.

The engine control module (ECM) compares the signal with the signal from the atmospheric pressure sensor in the engine control module (ECM). The fuel pressure is regulated so that the pressure in the fuel rail is always 380 kPa above the atmospheric pressure (i.e. the difference in pressure is 380 kPa).

Depending on factors such as engine speed and load, the engine control module (ECM) transmits a calculated pulse width modulated (PWM) signal to the control module for the fuel pump (FP). The control module for the fuel pump sends the signal on to the fuel pump at a higher frequency.

The PWM signal corresponds to a certain feed voltage to the pump. This in turn corresponds to a certain pump flow rate. By adapting the supply voltage, the load of the pump matches the fuel requirement.

If the engine is running at higher engine speeds (RPM) and under high load, the speed of the pump is higher (greater flow) than at small loads and low engine speed (RPM).

If the pressure briefly rises to 400 kPa, during acceleration for example, the fuel flow is compensated by reducing the injection period. For longer periods of time, such as a couple of seconds, the fuel pressure is lowered via the fuel pump to compensate.

A diagnostic trouble code (DTC) is stored If the pressure sensor detects that the pressure remains at the same value for a long time. The emissions warning lamp lights if the same fault persists or returns.

A diagnostic trouble code (DTC) is stored in the fuel pressure system if there is no signal from the pressure sensor or if it is implausible. The fuel pump (FP) is controlled using a PWM signal. The signal is calculated from the fuel flow - based on the injection periods and the desired pressure.