Fuel Delivery and Air Induction: Description and Operation

GF07.61-P-3004MIS ME Fuel Supply, Function
- as of model year 09

Component Identification:

Function requirements for fuel supply, general points
^ Circuit 15 ON (ignition ON)
^ Circuit 87M ON (engine control ON)

Fuel supply, general points
In all operating conditions, the fuel supply delivers filtered fuel to the injection valves from the fuel tank, in sufficient quantity and at sufficient pressure (injection pressure).

Fuel supply, function sequence
The fuel supply function sequence is divided into the following points:
^ Fuel pump actuation function sequence
^ Fuel delivery function sequence

Fuel pump actuation function sequence
The fuel pump is switched on when the fuel pump control unit receives the "fuel pump ON" ground signal from the ME-SFI [ME] control unit (N3/10)(N118).
The fuel pump control unit detects the current fuel pressure through the voltage signal from the fuel pressure sensor.
The fuel pump control unit evaluates the current fuel pressure, compares it with the preset specified value of 3.8 bar, and actuates the fuel pump with a pulse width modulated signal (PWM signal) as required, so that the actual value corresponds to the specified value.

The fuel pump control unit sends the current fuel pressure over the drivetrain CAN (CAN C) to the ME-SFI [ME] control unit.

Fuel delivery function sequence
The fuel pump draws fuel from the bottom of the fuel feed module and pumps it through the fuel filter to the fuel distribution pipe (single line system).
The fuel pressure is limited to 3.8 bar by the fuel pressure regulator.

There is a check valve in the fuel line to the fuel filter which prevents loss of fuel pressure when the fuel pump is switched off.

The fuel return from the fuel pressure regulator supplies fuel to the suction jet pump in the LH fuel tank chamber.
This suction jet pump delivers the fuel out of the left fuel tank chamber into the fuel feed module (in the right fuel tank chamber) and thus prevents single-sided emptying of the fuel tank.