Fuel pump control unit, function - GF47.20-P-4009-02MA

The fuel pump control unit actuates the fuel pump (M3) dependent on the fuel pressure sensor (B4/7) signal in such a way that the fuel system pressure is constant at about 3.8 bar.

If the system pressure detected by the fuel pressure sensor drops below approx. 3.8 bar, the switch-on time of the PWM signal is extended. Power consumption, rpm and delivery rate of fuel pump increases.

If the issued on/off ratio to the fuel pump (M3) is more than 5 seconds greater than 72 %, the intank fuel pump relay is actuated with a ground signal via another output on the fuel pump control unit. The intank fuel pump (M3/1) is operating.

For model 230 from about 1.3.06 the intank fuel pump and the intank fuel pump relay are not needed.