3 Series E46 320d (M47) SAL
line. This prevents the fuel from being excessively heated at high outside temperatures.
Large and heated amounts of return fuel occur under extreme operating conditions such as e.g. uphill driving or trailer
towing. For this reason, part of the fuel is routed directly into the fuel feed line by the flow restrictor in the H-piece. This
measure also counteracts any excessive heating of fuel in the fuel tank.
M57 (see drawing 5.2)
The fuel is routed from the electric fuel supply pump via the fuel feed line, the inline pump and the fuel filter to the high-
pressure pump.
The high-pressure pump supplies the injection nozzles with fuel via the fuel rail.
The inline pump generates the necessary preliminary fuel pressure for the high-pressure pump. This preliminary
pressure is maintained at a constant level by the pressure limiting valve in the engine circuit.
The return fuel from the fuel injectors and the high-pressure pump is directed to the bimetallic valve, which divides the
amount of return fuel as a function of the fuel temperature.
At low fuel temperatures, the greater part of the fuel flows directly into the fuel feed ahead of the inline pump. In this
way, the fuel is heated up faster at low outside temperatures.
At high fuel temperatures, the greater part of the fuel flows back into the fuel tank via the fuel cooler and the fuel return
line. This prevents the fuel from being excessively heated at high outside temperatures.
Large and heated amounts of return fuel occur under extreme operating conditions such as e.g. uphill driving or trailer
towing. For this reason, part of the fuel is routed directly into the fuel feed line by the flow restrictor in the H-piece. This
measure also counteracts any excessive heating of fuel in the fuel tank.
Venting system (see drawing 5.1 / 5.2)
The fuel tank is vented during refueling via the refueling vent line in the filler necks.
During driving, the fuel tank is vented via the service vent lines and the expansion tank.
The condensed constituents of the fuel vapors pass from the expansion tank via the left service vent line back into the
fuel tank.
Determining fill level in fuel tank
The fuel level is measured by means of lever-type sensors on both sides of the fuel tank. The right lever-type sensor is
integrated in the fuel supply unit. The left lever-type sensor is located in the left sensor unit. The combination of the
determined ohm values from the right and left lever-type sensors produces the actual level in the fuel tank.
4. Service data, fuel system
Working pressure of fuel supply pump: 0.4 bar
Working pressure of suction jet pump: 1 - 1.3 bar
5. Schematic drawings of fuel supply systems
RA Fuel supply system E46 (diesel engines)
BMW AG - TIS
12.02.2013 13:50
Issue status (12/2007) Valid only until next DVD is issued
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