Engine Misfires Under Load

SYMPTOM DESCRIPTION:

Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. The exhaust has a steady spitting sound at idle or low speed.




POSSIBLE CAUSE ACTION

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

^ Change fuel filter.




Empty fuel tank or ^ Fill tank.
fuel tank vent blocked ^ Bleed fuel system.

^ Check tank vent.






Air in fuel system ^ Bleed fuel system.






Clogged fuel filter ^ Replace fuel filter.





Restricted, blocked, damaged ^ Remove restriction or
or leaking fuel injector lines replace lines as necessary.
Bleed fuel system.





Leaking or damaged fuel ^ Replace leaking or damaged
supply lines, or loose lines or tighten connections as
fuel connections needed. Bleed fuel system.





Incorrect injection pump to ^ Adjust injection pump timing.
engine timing




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





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