Fuel System Control Unit, Basic Function - GF47.00-P-9900A

Engine all (CAR) 

Courtesy of MERCEDES-BENZ USA

Schematic diagram of low-pressure and high-pressure fuel circuit 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 

General 

The fuel system provides the combustion engine with fuel in all operating ranges by means of the fuel supply system and mixture formation system. Function requirements 

• Engine management ON (terminal 87M)
• Ignition ON (circuit 15) Function 

The fuel system consists of the fuel supply system (low-pressure fuel circuit) and the mixture formation system (high-pressure fuel circuit). The fuel supply system pumps the fuel from the fuel tank to the high-pressure fuel pump.

The mixture formation system consists of the high-pressure fuel circuit and the injection control. The mixture formation system compresses the fuel via the high-pressure fuel pump, stores the fuel pressure in the fuel distributor and, depending on the operating condition, supplies the fuel to the fuel injectors. To form an optimum fuel/air mixture, the fuel injectors inject as much fuel as is needed directly into the combustion chamber.

Key components of fuel supply system (low-pressure fuel circuit):

• Fuel tank
• Fuel feed module
• Fuel filter module (diesel engines)
• Fuel pump control unit
• Fuel preheating control unit (diesel engines)
• Fuel pressure and temperature sensor

Key components of mixture formation system (high-pressure fuel circuit):

• Fuel high-pressure pump
• Fuel distributor
• Fuel injectors
• Fuel distributor fuel pressure sensor
• Quantity control valve
• Pressure limiting valve
• High-pressure fuel lines