5 Series E39 528i (M52) SAL
The fuel is routed from the electric fuel supply pump via the fuel feed line and the fuel filter to the fuel rail. The fuel
returns to the fuel tank via the pressure regulator secured to the fuel rail and the fuel return line.
M52 USA and M73 (see drawing 5.2/ 5.3)
The fuel is routed from the electric fuel supply pump via the fuel feed line and the fuel filter to the fuel rail.
The fuel returns to the fuel tank via the 3/2-way valve (see view A), the pressure regulator and the fuel return line.
This engine fuel circuit with return from the fuel rail is then switched for engine starting and a defined time < 1 minute.
After this phase, the 3/2-way valve switches and interrupts the fuel return from the fuel rail. At the same time, the line
branch directly at the fuel filter is activated by the 3/2-way valve to the pressure regulator (see view B).
The fuel rail is now return-free.
M62TU/54 (see drawing 5.1, view B, and drawing 5.4/ 5.5)
Pressure regulator and fuel filter are incorporated in a single unit.
The fuel is routed from the electric fuel supply pump via the fuel feed line and the fuel filter/pressure regulator unit to
the fuel rail.
The fuel rail is return-free. The fuel flows directly from the fuel filter/pressure regulator unit back into the fuel tank.
Venting system USA (see drawing 5.3/ 5.4 / 5.5)
The fuel tank is vented during refueling via the refueling vent line.
Because of its large cross-section, the refueling vent line directs the displaced volume (fuel vapors) at high speed
through the expansion tank to the carbon canister.
The activated carbon retains the fuel contained in the fuel vapors. The cleaned air is discharged to atmosphere via the
evaporation line, the leakage diagnosis pump or the tank leakage diagnostic module and the dust filter.
During driving, the system tank is vented in the same way via the refueling vent line and service vent line.
The condensed constituents of the fuel vapors pass from the expansion tank via the service vent line back into the fuel
tank.
The float valve in the refueling vent line (E39 only) is closed by the rising fuel if the tank is overfilled. This prevents
overflowing of the expansion tank.
The roll-over valve on the upper side of the expansion tank closes in the event of the vehicle overturning. This prevents
the fuel from escaping into the carbon canister.
The carbon canister is regenerated by purging with fresh air.
The engine control unit opens the tank vent valve. Thus the vacuum pressure of the engine intake manifold is applied
at the purge line.
In this way, the carbon canister is purged by the supply of fresh air via the evaporation line, the leakage diagnosis
pump or the tank leakage diagnostic module and the dust filter. The fuel constituents bound by the activated carbon are
flushed out by the supplied air and directed via the purge line to the engine for combustion.
This operation is only possible while the engine is running.
Venting system worldwide (see drawing 5.1/ 5.2)
Refer to Venting system USA with following differences:
1.
During refueling, the fuel tank is vented via the refueling vent line, which directs the displaced volume into the filler
neck. There is a second service vent line with a smaller cross-section in place of the refueling vent line (USA) with
large cross-section. There is no float valve.
2.
The carbon canister has a smaller capacity.
RA Fuel supply system E38 / E39 (spark-ignition engines)
BMW AG - TIS
21.02.2013 16:55
Issue status (12/2007) Valid only until next DVD is issued
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