1 Series E81 130i (N52K) 3-door
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Notes on fuel pressure check (reference pressure: environment)
Feature of this version with ambient pressure:
The connection for the vacuum hose of the fuel pressure regulator is located between the throttle and the air
cleaner or on the air cleaner.
Test precondition:
The correct fuel pressure regulator is fitted.
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Using the EPC, check whether the fuel pressure regulator suitable for the car is fitted:
Connect test adapter.
Description of operation:
The control function of the fuel pressure regulator must be guaranteed under all operating conditions. The fuel pump
must always be able to generate a higher fuel pressure than the pressure regulated by the pressure regulator.
The injection rate is adjusted by means of the injection time; the injection time is controlled by the DME.
Description of operation: fuel return line
When the engine is at a standstill and the ignition key is in position 0, the fuel return line after the pressure regulator is
at zero pressure.
Description of operation: pressure retaining function
The pressure regulator closes when the engine is at a standstill and the ignition key is in position 0. The fuel pressure
in the delivery line is retained over an extended period. A non-return valve closes in the fuel pump. These measures
help to retain the fuel pressure in the fuel system. Extended starting times are thus avoided.
Complaint: drive characteristic faults, lack of power
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Run engine at idle speed and measure fuel pressure.
If the measured value is less than the nominal value - 0.2 bar:
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Line cross-sections in fuel feed are constricted or fuel filter is clogged,
or
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Fuel pump voltage supply is not O.K.: e.g. as a result of high contact resistance (corrosion) in plug
connection between wiring harness and fuel pump.
If the measured value is greater than the nominal value + 0.2 bar:
-
Turn off engine stop and then observe measured value.
-
If measured value drops to nominal value, then line cross-sections in fuel return are constricted or
clogged.
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Check the fuel lines for kinks.
If no kinks are visible:
-
Replace return lines
If measured value remains too high, then pressure regulator is in all probability faulty.
Important:
With less likelihood, the return line may be completely blocked. When the pressure regulator is removed, fuel could
RA Notes on fuel pressure check (reference pressure: environment)
BMW AG - TIS
22.01.2013 03:48
Issue status (12/2007) Valid only until next DVD is issued
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