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Failure to start, suspecting high-pressure fuel pump to be the culprit.


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Hello everyone, I have been a long-time reader, but this is my first post.

I just acquired a non-operational 2004 X3 2.0d equipped with the M47 engine, and I am experiencing fuelling problems. I first observed the absence of an injector pulse and was then informed that injector pulsing requires rail pressure. I then used INPA to verify the pressure, which increased to 400 while cranking. I unplugged one of the injectors and reconnected it inverted to see whether it sprays, but there was no output.

I then loosened one of the gasoline lines to see whether it would relieve pressure; however, it only dribbled out.

I subsequently examined the fuel supply from the low-pressure fuel pump to the rail and high-pressure fuel pump, confirming that both the rail and high-pressure fuel pump are receiving an ample fuel supply.

I then examined the fuel pressure regulator located behind the high-pressure fuel pump and did not see a click; nonetheless, it was receiving 9 volts with the ignition activated. I disconnected it and supplied power straight, resulting in a click.

I ultimately ruptured the line connecting the high-pressure fuel pump to the rail and saw that no gasoline was emerging.

The only issues in the vehicle are the glow control unit and the camshaft position sensor, signals (3EC0, 3EC1). I replaced the sensor, but the error persisted; thus, I inspected the wiring, which is intact. I have been informed that a malfunctioning camshaft position sensor might inhibit the vehicle from starting; however, I have replaced the sensor and inspected the wiring, still the issue persists.

I have been informed that a malfunctioning injector may be the culprit, since these injectors tell the ECU to terminate fuel delivery upon failure, resulting in a lack of injector pulse (as stated by a representative from Bosch).

I saw in many discussions that upgrading the ECU resolved this issue for others who encountered it. It is worth noting that the ECU was defective when I purchased the vehicle, but I had it repaired, and it successfully passed all bench tests.

I believe the high-pressure fuel pump is the problem, albeit I am not a technician.

Your assistance would be much appreciated.

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