Fuel Pump: Description and Operation

GF47.20-P-2000MOR Component Description For Fuel Pump
- ENGINES 275.954 in MODEL 230.477 as of Model Year 09 /Modification Year 08 model refinement package
- ENGINES 275.981 in MODEL 230.479 as of Model Year 09 /Modification Year 08 model refinement package





View of underfloor
M3 Fuel pump
N118 Fuel pump control unit

Location
The fuel pump is located behind the rear axle on the underfloor.

Task
The fuel pump supplied fuel in sufficient quantity and at the required pressure to the fuel injection system (fuel distribution rail).





Design
1 Rotating spindle
2 Drive spindle
3 Check valve
4 Pressure relief valve
5 Electric motor
6 Ground connection
7 Power supply (12 V)
a Fuel from fuel tank
b Fuel to fuel filter with integrated fuel pressure regulator

The fuel pump consists of a jack screw pump.

Function
The fuel pump is actuated as required by the ME-SFI control unit (N3/10) through the fuel pump control unit (N118).

The fuel pump draws fuel from the bottom of the fuel tank swirl pot through a fuel strainer.
The rotating jack screw delivers fuel to the fuel filter by centrifugal force.

A pressure relief valve is integrated in the fuel pump to limit the internal pressure.
The check valve in the fuel pump decouples the fuel system from the fuel tank, by preventing the backflow of fuel to the fuel tank when the fuel pump is switched off.