SERVICE DIAGNOSIS
-
PERFORMANCE (GGNT.)
CONDITION
POSSIBLE
CAUSES
COKKBCTSON
ROUGH
IDLE
(IRREGULARLY
FIRING
OR
ENGINE
SHAKING)
(Cont'd)
High
pressure
fuel leaks.
Air in the fuel
system.
Correct
leaks
in
the
high
pressure
lines,
fittings or
delivery
valves.
Bleed
the
fuel
system and eliminate the source
of
the air.
Sticking
needle
valve
in
an
injector.
Check
and
replace
the
injector
with the
sticking
needle
valve.
ENGINE
RUNS ROUGH
OR
MISFIRING
Fuel
injection lines
leaking.
Correct
leaks
in
the high pressure
lines,
fittings, injector sealing
washers
or
delivery
valves.
Air in
the
fuel or the fuel
supply
is
inadequate.
Check
the
flow
through the
filter
and bleed the
system.
Locate
and eliminate the
air
source.
Contaminated
fuel.
Verify
by
operating
the engine
with
clean fuel
from
a
temporal,
supply
tank. Check
for
presence
of
gasoline. Replace fuel/water
separator
filter.
Incorrect
valve
adjustment.
Check
for
a
bent push rod and adjust
valves.
Replace push rod,
if
necessary.
Injection
pump
timing
incorrect.
Check/time
pump
(refer
to
Group 14, Fuel System).
Improperly
operating
injectors.
Replace
inoperative
injectors.
Defective
injection
pump
(delivery valves).
Replace
injection
pump.
Camshaft
out of
time.
Check/correct
gear train
timing
alignment.
Damaged
camshaft
or
tappets.
Inspect
camshaft
valve
lift.
Replace camshaft and tappets.
ENGINE
RPM
WILL
NOT
REACH
RATED
SPEED
Engine
overloaded.
Verify
high
idle
speed
without
load. Investigate operation
to be
sure
correct gear is being
used.
Improperly
operating
tachometer.
Verify
engine speed
with
hand tachometer-—correct as required.
Throttle
linkage
worn or
incorrectly
adjusted.
Adjust
linkage
for
stop-to-stop fuel control lever travel. Replace
linkage
if
necessary.
Partially
engaged
mechanical
shutdown
lever.
Adjust
and place shutdown lever
in
the run position.
Inadequate
fuel
supply.
Check
the
fuel
flow through the system
to
locate the reason
for
inadequate
fuel
supply—correct
as
required.
Improperly
operating
injection
pump.
Replace
injection
pump.
LOW
POWER
Fuel
control
lever not
moving
to
full
throttle.
Check/correct
for
stop-to-stop travel.
Mechanical/shutdown
lever
partially
engaged.
Check
to
see
if
the shutdown lever is
in
run position.
High
oil
level.
Check/correct
oil
level.
Engine
overloaded.
Check
for
added
loading
from
accessories
or
driven units, brakes
dragging
and
other
changes
in
vehicle
boding.
Repair/replace
as
needed.
J9109-264
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