3 Series E46 316i (M43TU) SAL
10. Overflow protection valve
25. Flush line
11. Rollover valve
26. Vent line
12. Operating vent line
27. Activated carbon filter
13. Refuelling vent line
28. Breather pipe
14. Pressure-maintenance valve
29. Dust filter
15. Throttle
30. Tank leak diagnosis module (USA only)
3.2 Functional description (please refer to drawing 3.4)
Fuel system
The fuel tank is equipped with a surge chamber with electric fuel delivery pump.
The surge chamber guarantees correct fuel supply from the fuel delivery pump in all operating states of the vehicle.
The suction jet pump installed in the base of the surge chamber supplies the surge chamber with fuel.
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 filler neck is divided into two in the fuel tank. This ensures that the tank can be filled quickly. The two check
valves prevent the fuel from sloshing back in the fuel filler neck when the fuel pump nozzle cuts off.
Fuel supply to the engine
For description, please refer to "Fuel supply system E38/39,
1.2 Functional description, fuel supply system for engine M54/62".
Ventilation system USA
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
condensation reservoir 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 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 condensation reservoir into the fuel tank
through the operating vent lines.
The rollover valves in the vent lines prevent fuel from reaching the condensation reservoir in extreme vehicle
conditions and positions.
The throttle in the right-hand operating vent line prevents the fuel tank from being overfilled when refuelling. When
the specified volume has been reached, the rollover valve will close the refuelling vent line. The system is then only
vented through the operating vent lines. If you then continue refuelling, the throttle will generate overpressure in the
fuel tank. This will create an obstacle to continued refuelling. The pressure-maintenance valve in the left-hand
operating vent line limits the overpressure in the fuel tank.
The activated carbon filter is regenerated by flushing out with fresh air.
The engine control unit opens the fuel evaporation control valve. This applies the vacuum generated in the engine
intake manifold to the flush line.
In this way, the activated carbon filter is flushed out with a supply of fresh air through the tank leak diagnosis module
and the dust filter. The components of fuel gathered by the activated carbon filter are fed into the engine's
combustion through the air supply and the flush line.
This process is only possible with the engine running.
Ventilation system - all countries
Please refer to ventilation system USA with the following differences:
1.
The activated carbon filter has a smaller capacity.
2.
The tank leak diagnosis module (please refer to drawing 3.4, view A) is eliminated.
SBT Functional description of fuel supply system E38 E39 E46 E52 E53
BMW AG - TIS
19.01.2013 20:41
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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