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Common faults and diagnosis of fuel injection pump

Sep 03,2025

Reason: Wear of plunger components, clogged fuel filter, and oil leakage. Performance: Decreased engine power and black smoke coming from the exhaust pipe.

1. Common faults
Insufficient fuel supply:
Reason: Wear of plunger components, clogged fuel filter, and oil leakage.
Performance: Decreased engine power and black smoke coming from the exhaust pipe.
Low fuel supply pressure:
Reason: Poor sealing of the oil outlet valve, rupture of the high-pressure oil pipe, and wear of the camshaft.
Performance: Difficulty starting and unstable idling.
Uneven fuel supply:
Reason: Stuck plunger components, faulty governor, and worn oil control mechanism.
Performance: Engine vibration and abnormal noise.
Fuel leakage:
Reason: Aging of seals, cracking of plunger sleeve, and loosening of oil outlet valve seat.
Performance: Increased fuel consumption and water ingress into the oil pan (in case of severe leakage).
2. Fault diagnosis methods
Pressure test: Use a fuel pressure gauge to measure the pressure of the high-pressure fuel pipe and determine whether the fuel injection pump is leaking or the pressure is insufficient.
Flow test: measure the fuel injection amount per unit time and evaluate the degree of wear of plunger components.
Endoscopic inspection: Disassemble the fuel injection pump and use an endoscope to observe whether there are scratches or carbon deposits on the surface of the plunger.
Sound analysis: Abnormal noise may indicate a stuck plunger or a faulty oil outlet valve.
ECU fault code reading: For the electronic fuel injection pump, read the fault code through the diagnostic instrument (such as P0201-P0208 indicating a fault in the fuel injector circuit).