3 Series E46 316i (N40) SAL
10. Fuel filler cap
27. Flush line
11. Pressure check line (USA only)
28. Vent line
11. Refuelling vent line (all countries)
29. Vacuum line (leak diagnosis pump USA only)
12. Fuel feed line
30. Breather pipe
13. Fuel return line
31. Activated carbon filter
14. Operating vent line
32. Activated carbon filter (USA only)
15. Refuelling vent line (USA only)
33. Leak diagnosis pump (USA only)
15. Auxiliary vent line (Japan)
34. Dust filter (USA only)
16. Operating vent line
35. Tank leak diagnosis module (USA only)
17. Expansion tank
2.2 Functional description (please refer to drawing 2.4/2.5/2.6/2.7)
Fuel system
The right-hand side of the saddle-shaped fuel tank has a surge chamber with the electric fuel delivery pump.
The surge chamber guarantees correct fuel supply from the fuel delivery pump in all operating states of the vehicle.
Fuel is transferred from the right-hand side of the fuel tank to the surge chamber by the suction jet pump integrated in
the tank expansion line. The suction jet pump is driven by the fuel return line.
The pressure relief valve controls the pressure required for the suction jet pump to operate. The overflow protection
valve protects the fuel return line. Should the pressure drop in the event of damage or the fuel return line becoming
separated, the valve will close.
This prevents the fuel from overflowing from the fuel tank in extreme vehicle positions (rollover, inclination).
The non-return flap prevents the fuel from sloshing back in the fuel filler neck when the fuel pump nozzle cuts off.
Fuel supply to the engine
M43TU/52TU (please refer to drawing 2.4, view A)
For description, please refer to "Fuel supply system E38/39,
1.2 Functional description, fuel supply system for engine M52TU".
M52 USA and M73 (please refer to drawing 1.5/1.6)
For description, please refer to "Fuel supply system E38/39,
1.2 Functional description, fuel supply system for engine M52 USA and M73".
M54 (please refer to drawing 1.4, view B and drawing 1.7/1.8)
For description, please refer to "Fuel supply system E38/39,
1.2 Functional description, fuel supply system for engine M54/62TU".
Ventilation system USA (please refer to drawing 2.6/2.7)
When refuelling, the fuel tank is ventilated through the refuelling vent line.
Due to its large cross-sectional area, the refuelling vent line quickly feeds the displayed volume (fuel vapours) via the
expansion tank to the activated carbon filter.
The activated carbon absorbs the fuel contained in the fuel vapours. The purified air is then fed into the atmosphere
through the breather pipe, the leak diagnosis pump or the tank leak diagnosis module and dust filter.
Ventilation during operation of the vehicle is maintained in the same manner through the refuelling vent line and
operating vent line.
The condensed components of the fuel vapours are fed back from the expansion tank into the fuel tank through the
left-hand operating vent line.
In the event of overfilling, the float valve in the expansion tank will be closed by the rising fuel level. This prevents the
expansion tank from filling.
The rollover valve on the top of the expansion tank will close in the event of the vehicle turning over. This prevents
the fuel from escaping into the activated carbon filter.
SBT Functional description of fuel supply system E38 E39 E46 E52 E53
BMW AG - TIS
20.01.2013 12:36
Issue status (12/2007) Valid only until next DVD is issued
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