BMW engine fuel pump and ignition problems – what is the cause and how to fix it?

BMW driver’s question about engine ignition problems

For some time now I have a problem with starting the car after a long stop – for example, after a night out. The fuel filter was replaced, but the fault still remains.

The car fires up, but after literally one or two seconds it goes out. After the second firing it behaves as it should. There are no errors on the computer. I noticed that when I give the key to position 1 and wait 10 seconds, then to position 0 and repeat the action, again counting down 10 seconds, the car fires up with no problem. What could be the cause and what would need to be replaced?

The problem affected a 2007 BMW X3 E83 with a 2.0 diesel engine, but it may also occur in other models.

BM Cars service response – fuel pump and engine ignition problems in a BMW

The described symptoms and behavior of the engine suggests in the first place a problem with the supply of sufficient fuel. Restarting the engine solves the problem because the fuel pump has replenished the fuel in the fuel lines and high-pressure pump. This usually happens when there are leaks in the fuel system.

Prolonged stopping causes air to enter the fuel system and the fuel to back up into the tank. Starting the engine again requires pumping fuel into the high-pressure pump. Therefore, trying to pump fuel without starting the engine – turning the key to position 1 several times – solves the problem.

Leaks in the fuel system can be caused by a leak in the high-pressure pump – fuel leaks or leaks on the fuel lines and their connections usually with hose clamps. Sometimes a similar problem occurs when:

• the fuel filter was clogged (too infrequent replacement of the fuel filter),
• the fuel filter was incorrectly selected,
• the fuel filter was installed the opposite way than it should have been.

It is extremely rare that the fuel pump is damaged. In the fuel system of the M47 engine, the low-pressure fuel pump is located in the fuel tank. If the vehicle is used frequently with very little fuel (deep reserve), it can overheat and be damaged. Then the pre-pressure supplied by this pump and its capacity will be insufficient.

We suggest doing the following:

1. Full diagnostics of the engine with special emphasis on the fuel system – measuring fuel pressure in the low and high pressure range.
2. Verification of the tightness of the fuel system, removal of leaks.
3. Diagnosis of the correct installation and proper selection of the fuel filter.
4. Verification of the tightness of the injection pump and injectors.
5. If abnormal pressures are found during diagnosis – repair/replacement of the fuel pump or injection pump.

We offer all the listed steps in our service.

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