Engine Idles Rough When Warm

SYMPTOM DESCRIPTION:

The engine runs unevenly at idle. If bad enough, the vehicle may shake. Also, the engine may hunt (idle rpm unstable). Either condition may be severe enough to cause stalling. Engine idles at incorrect speed.




POSSIBLE CAUSE ACTION

Improper fuel ^ Drain fuel tank, flush system,
and fill with proper fuel.

^ Change fuel filter.


Air in fuel system ^ Bleed fuel system.



Low idle speed ^ Adjust idle speed



Loose injection pump rear ^ Tighten bracket with
support bracket engine OFF.



Damaged or restricted injector ^ Clean or replace injector
nozzle nozzles.



Fuel injection sequence ^ Check fuel injection lines
does not correspond with for proper routing.
firing order




Low or uneven engine ^ Repair as necessary.
compression




Malfunctioning KSB valve/ ^ Check KSB valve function.
injection pump If KSB valve is found to
be defective, replace injection
pump.

^ If injection pump is malfunctioning
or will not adjust properly, replace as
a unit.