| Cause |
Correction |
| Conditions only occurs at idle |
See - Engine runs rough at idle |
| Engine is cold |
Allow the engine to warm up to
operating temperature. If engine will not reach operating
temperature see manual. |
| Fuel injection lines are leaking |
Inspect/correct the leaks in
the high pressure lines, fittings, or delivery valve gaskets. |
| Fuel supply inadequate |
Check the flow through the filter
to locate the source of the restriction |
| Air in the fuel system |
Bleed the fuel system and check
for suction leaks |
| Malfunctioning fuel return overflow
valve |
Check/replace the return overflow
valve |
| Fuel transfer pump malfunctioning |
Check/replace the fuel transfer
pump |
| Fuel Supply restricted |
Clean the pre-filters and screens
and check the fuel line for restrictions. |
| Fuel contaminated |
Verify by operating the engine
with clean fuel from a temporary tank. |
| Valves incorrectly adjusted (valves
are not sealing) |
Check and adjust the valves |
| Injection pump timing |
Check and adjust the timing of
the injection pump to the engine manufacturer's specifications. |
| Engine compression is low |
Perform the compression check
to identify the malfunction. |
| Injectors worn or malfunctioning |
Check the injectors and replace
any malfunctioning injectors |
| Fuel injection pump malfunctioning/delivery
valves are malfunctioning |
Remove the fuel injection pump
and repair or replace as necessary |
| Camshaft is out of time |
Check/correct the gear train
timing alignment |
| Camshaft, tappets, or push rods
are damaged |
Inspect the camshaft and tappets |
