Fuel Tank, Function

Fuel Tank, Design




45 Filler neck
55/2 Fuel filter with fuel pressure regulator
75 Fuel tank
88 Fuel delivery module
92 Fuel pressure line to engine
B4/1 Fuel level sensor, left half of tank
B4/2 Fuel level sensor, right half of tank
B4/3 Fuel tank pressure sensor (USA)
M3 Fuel pump (FP)




55/2 Fuel filter with fuel pressure regulator
55/2a Fuel pressure regulator
88 Fuel delivery module
92 Fuel pressure line to engine (controlled fuel pressure)
95 Suction spray pump B4/1 Fuel gage sensor, left half of tank
B4/2 Fuel gage sensor, right half of tank
M3 Fuel pump (FP)
A Return flow from fuel pressure regulator to fuel delivery module
B Fuel pressure line from fuel pump to fuel filter (uncontrolled fuel pressure)
C Fuel delivery line from suction jet pump to fuel delivery module
D Fuel pressure line for supplying suction jet pump

The fuel flows from the two-stage fuel pump (M3) into the fuel delivery module (88), out of the right fuel tank chamber, through the fuel pressure line (B) to the fuel filter with fuel pressure regulator (55/2) into the left fuel tank chamber.

A junction with the fuel pressure line (D) supplies the suction jet pump (95). A suction effect is produced in the suction jet pump which draws the fuel from the deepest point out of the left fuel tank chamber to the fuel delivery module. (C).

Moreover excess fuel flows from the fuel pressure regulator to the fuel delivery module ( A).
This ensures that the left fuel tank chamber is properly emptied.

The filtered fuel with controlled fuel pressure is supplied to the engine via the fuel pressure line (92) (single-line system).

The housing of the fuel delivery module serves as a swirl pot. When cornering with a low level of fuel in the fuel tank, it prevents the fuel pump drawing in air.
A fuel strainer is installed at the bottom in the fuel delivery module at the feed to the fuel pump.

Each fuel tank chamber has a fuel level sensor (B4/1, B4/2). Both resistance values are transmitted separately to the rear SAM control unit with fuse and relay module (N10/2) which transmits the corresponding signals via the CAN databus to the instrument cluster.

Note: The fuel tank has no outlet valves. It is drained through the fuel pump via the fuel line in the engine compartment.