Fuel Pump: Description and Operation

GF47.20-P-2000MLK Component Description For Fuel Pump
- ENGINES 113.989 in MODEL 171.473 as of Model Year 09 /Modification Year 08 model refinement package





Sectional view of fuel tank
75 Fuel tank
76 Fuel pump assembly
B4 Fuel level sensor
M3 Fuel pump

Location
The fuel pump is integrated in the fuel pump assembly, which is inserted in the fuel feed module.

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

Design
The fuel pump is a two-stage flow pump with a minimum delivery rate of 130 liters/hour at 3.8 bar.

A fuel strainer is installed in the fuel pump feed line (as fuel prefilter).

The suction jet pump is integrated at the bottom of the fuel pump assembly, and is supplied with fuel by the fuel pump.

Function
The fuel pump is actuated by the ME-SFI control unit (N3/10) through the fuel pump relay (N10/2kA).

The fuel pump draws fuel from the bottom of the fuel feed module through the fuel strainer. It then pumps the fuel to the fuel distribution rail through the fuel filter with fuel pressure regulator.
The fuel pressure is limited to about 3.8 bar by the fuel pressure regulator.

When the fuel level is low in the fuel tank, the suction jet pump fills the fuel feed module with fuel from the fuel tank.