Fuel Pump: Description and Operation

GF47.20-P-2000IC Component Description For The Fuel Pump
- ENGINE 647.961 in MODEL 211
- ENGINE 648.960 in MODEL 220
- ENGINE 648.961 in MODEL 211





Location on model 211
1 Fuel delivery module
M3 Fuel pump

The fuel pump is integrated in the fuel feed module and is located in the right fuel tank chamber.





Location on model 220
M3 Fuel pump

The fuel pump is located at the bottom left on the vehicle underbody.

Task (models 211, 220)
The fuel pump provides a sufficient quantity of fuel to the high-pressure pump and at the required pressure.

Structure (model 211)
The fuel pump is a two-stage flow pump.
A fuel strainer is installed as a rough filter below on the inlet to the fuel pump.

Function (model 211)
The fuel pump is actuated via the fuel pump relay(N10/2kA) by the CDI control unit (N3/9).
It draws the fuel from the fuel feed module through a fuel strainer. The fuel pump then pumps the suctioned in fuel over the fuel filter to the high pressure pump.





Body (model 220)
1 Rotating spindle
2 Drive spindle
3 Check valve
4 Pressure relief valve
5 Electric motor
6 Ground supply
7 Voltage supply
a Fuel from fuel tank
b Fuel to the fuel filter

The fuel pump is designed as a helical spindle pump.

Function (model 220)
The fuel pump is actuated via the fuel pump relay (K40/5kT) by the CDI control unit (N3/9).
The rotating spindle (1) delivers the fuel to the fuel filter by the centrifugal force effect. In this case the fuel pump delivers more fuel than the engine needs in total in order to maintain the pressure in the fuel system in all operating states.

A pressure relief valve (4) is integrated in the fuel pump in order to limit the pressure.
The check valve (3) in the fuel pump decouples the fuel system from the fuel tank by preventing fuel from flowing back through the disconnected fuel pump to the fuel tank.