2009 BMW 335d Diesel Injection Pump Replacement Cost

The diesel injection pump produces the high fuel pressure required by diesel fuel injectors. Its shaft rotates in time with the engine, allowing it to send a high pressure fuel pulse to each injector at the proper time.

The diesel injection pump, also called high pressure fuel pump (HPFP), is driven, on most vehicles, by the timing chain, timing belt, or timing gear. It receives slightly pressurized fuel from the fuel tank in a large volume, and attempts to compress the liquid, resulting in a moderate flow at an extremely high pressure. In fact, the fuel line pressure this pump creates can reach 27,000 PSI at high engine speeds. This high pressure is needed to provide diesel to the engine as fast as fuel is needed.

Failure of the diesel injection pump can cause hard starting, cylinder misfiring, or a lack of power.

Hard starting, no starting or stalling immediately after starting are common symptoms of a failed or failing diesel injection pump. When the vehicle does start, misfires, loss of power and illumination of the check engine light for OBD codes relating to exhaust and emissions, fuel delivery, and misfires will be present. Also, getting the engine to speed up may be sluggish, and the engine may randomly surge with power.

After the fuel injection pump fails, the fuel distributor and injectors will not have sufficient power to drive the vehicle without severe driveability issues. Also, continuing to drive with a failed high pressure fuel pump could lead to metal shavings being passed through the fuel system as the fuel pump continues to spin. Since modern diesel fuel systems have return fuel lines, the metal shavings can make their way through the high pressure fuel pump, through the fuel distributor, to the injectors, and through the return line to the fuel tank, and back into the new LPFP, once replaced. To help avoid this costly repair, the vehicle should be towed to a repair facility.