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The Main Reason Why the Fuel Injection Pump Does Not Supply Oil

Nov. 22, 2019

The main reason why the diesel generator set fuel injection pump does not supply oil

1. There is no oil in the fuel tank or the oil switch is not open.

2. The diesel filter is clogged.

3. There is a lot of air in the oil road.

4. The plunger of the fuel injection pump is broken.

5. The plunger couple is excessively worn.

6. The plunger is stuck.

7. The screw groove of the plunger is installed in the wrong position.

8. The oil outlet valve is excessively worn or dirty.

9. The spring of oil outlet valve is broken or the spring force is weakened.

10. The plane contact between the oil outlet valve and the plunger sleeve is not strict, which causes the diesel oil to leak from the gap in the contact surface. The fuel valve is not opened at the top and the fuel injection pump is not supplied with oil.

11. The oil outlet valve is broken.


diesel generator set


Inspection method: If all cylinders do not supply oil, the diesel engine cannot work. If the individual cylinder does not supply oil, the diesel engine is difficult to start, even if started, the work is not stable. After finding this fault, first check if there is oil in the diesel tank, whether the fuel tank switch is open, and whether the vent hole of the fuel tank is blocked. Then unscrew the bleeder screw of the diesel filter and the fuel injection pump, pump the oil with the hand fuel pump or self-flow by the gravity of the diesel fuel. If there is air bubble in the diesel oil flowing out at the bleeder screw, it indicates that there is air in the oil pipeline. It should be found out that the reason is insufficient diesel oil in the fuel tank or the oil pipe joint is loose or the oil pipe is broken and the gaskets are not tight. After troubleshooting, continue to pump oil by hand oil pump or rely on the gravity of diesel to flow freely until there is no air bubble in the diesel oil. Then tighten the bleeder screw and the hand pump.


If the oil is pumped by the hand oil pump or the gravity of the diesel oil flows, it is felt that the oil is not smooth, indicating that the low pressure oil circuit is blocked. Check whether the diesel filter and the low pressure oil circuit are blocked. If there is oil leakage in the low pressure oil circuit, it will also cause the diesel oil to be blocked.

If there is no problem after inspection, the fault is inside the oil pump and should be disassembled and inspected. If there is no problem with the oil pump, the fault is on the fuel injection pump.


For the combined fuel injection pump, the side cover of the fuel injection pump can be removed here, the throttle handle is placed at the stop oil supply position, and the plunger spring seat of the fuel injection pump is pried by the screwdriver to perform the pump oil action, check whether the plunger spring is broken and whether the plunger is stuck.

At the same time, it should also check whether the screw that adjusts the ring gear is loose, resulting in changes in oil supply. If the inspection is good, check the wear degree of the plunger couple and the sealing of the oil outlet valve.

The main reason for the low fuel supply of fuel injection pump of diesel generator set

1. There is air in the fuel injection pump or oil pipe joint is loose and leaking oil.

2. The oil pressure is too low.

3. The oil supply amount adjusted by the plunger is too small, or the loosening of the locking screw of the ring gear is adjusted, so that the oil supply amount is too small.

4. The plunger couple is excessively worn.

5. The oil outlet valve is not tightly sealed.

6. The adjustment screw for limiting the maximum oil amount of the rack in the governor is too small or the throttle handle limit screw adjustment is too small.


Inspection method: After this fault is found, first check whether there is air in the fuel system and whether the oil pipe joint is loose and leaking. If there are no problems in these aspects, check whether the diesel/fuel filter and the low-pressure oil circuit are blocked; the oil supply of the fuel pump; whether the spring of the oil return valve is too weak. After inspection, all are good, the side cover of the fuel injection pump can be removed, check whether the locking screw of the adjusting ring gear is loose and displaced, or the adjusted oil supply is too small. If there is no such phenomenon, check the seal of the oil valve, the degree of wear of the plunger, the maximum oil adjustment screw and the throttle handle limit screw.


The above is the reason and inspection method for the diesel generator set fuel injection pump that does not supply oil or the amount of oil supply is too small. Starlight Power is specialized in the production of diesel generator sets, including Cummins generator set, Volvo generator set, Perkins generator set, etc., and is also one of leading manufacturers of diesel generators in China. Contact us to get the latest price of various brands of generators.

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