Engine runs rough or misfiring
| Cause | Correction | |
| Fuel injection lines leaking |
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Inspect / correct leaks in the high pressure lines, fittings injector sealing washers, or delivery valves. |
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| Air in the fuel or the fuel supply is inadequate |
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Check the flow through the filter and bleed the system. Locate and correct the air source. |
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| Contaminated Fuel |
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Verify by operating the engine with clean fuel from a temparary tank. |
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| Incorrect valve adjustment |
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Check for a bent push rod and adjust valves. |
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| Injection pump timing incorrect |
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Check / time pump. |
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| One or more cylinders has low compression |
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Preforma compression check to isolate the cause of low compression (piston rings, head gasket or valves). |
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| Malfunctioning injectos |
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Replace injectors. |
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| Defective injection pump (delivery valves) |
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Replace injection pump. |
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| Camshaft out of time |
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Chack / correct gear train timing alignment. |
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| Damaged camshaft or tappets |
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Inspect camshaft. |