Z Series E85 Z4 3.0i (M54) ROADST
canister.
The activated carbon retains the fuel contained in the fuel vapors. The cleaned air is discharged to atmosphere via the
evaporation line, the tank leakage diagnostic module and the dust filter.
During driving, the system tank is vented in the same way via the vent line.
The condensed constituents of the fuel vapors remain in the tank because the tank has an integrated compensating
volume.
The limiting valve in the tank is closed by the rising fuel if the tank is overfilled. The residual volume thus created
replaces the expansion tank. The ventilation function is maintained by a second float valve.
Both valves are designed as rollover valves. This prevents fuel from escaping from the fuel tank in extreme vehicle
positions (overturning, inclined position).
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. The carbon canister is purged in this way. The fresh air needed for this purpose is supplied via 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)
Refer to Venting system USA with following differences:
1.
The carbon canister has a smaller capacity.
2.
There is no tank leakage diagnostic module or dust filter.
Leakage detection for tank venting system USA (see drawing 5.2)
The tank leakage diagnostic module serves to detect leakages for the tank venting system within the on-board
diagnosis laid down by legislation.
The tank venting system is pressurized and the pressure loss is detected in the event of a leak.
The tank leakage diagnostic module detects the pressure loss by way of the power consumption of the integrated
pump. The air required for this purpose is supplied via the dust filter.
The systems is activated by the engine control unit.
The mushroom valve establishes by way of the vent line the connection between the fuel tank and the filler neck. This
enables a leak to be detected in the filler pipe - tank cap area.
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
Pressure regulator: 3.5 bar.
Working pressure of suction jet pumps: 1 - 1.3 bar
5. Schematic drawings of fuel supply systems
RA E85 fuel supply system (spark-ignition engines)
BMW AG - TIS
15.02.2013 12:52
Issue status (12/2007) Valid only until next DVD is issued
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