Poor Fuel Economy

SYMPTOM DESCRIPTION:

From an actual road test the measured MPG is noticeably lower than expected. At one time the fuel economy for this vehicle was at a greater average than current measurement.




POSSIBLE CAUSE ACTION

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

^ Change fuel filter.


Incorrect injection pump to ^ Check and/or Adjust
engine timing injection pump timing.


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


Clogged or restricted fuel ^ Replace fuel filter.
filter


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


Intercooler internally ^ Check pressure drop across
blocked or restricted inlet and outlet of intercooler.
If pressure drop exceeds 4 in. Hg,
clean or replace intercooler as
needed.


Low idle speed setting ^ Adjust low idle speed.
out of adjustment


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.