5.9L
(DIESEL) ENGINES
9
-
7
SERVICE
DIAGNOSIS
-
PERFORMANCE
(CONT.)
POSSIBLE
CAUSES
C01RECTION
ENGINE
HARD
TO
START,
OR WILL
NOT
START—SMOKE
FROM
EXHAUST
(Cont'd)
Fuel
pump inoperative.
Injection pump
throttle
linkage
loose
or damaged.
Contaminated
fuel.
Worn
or
inoperative injection
pump.
Injection pump out of time.
Valves
incorrectly
adjusted.
One
or
more
injectors
worn
or
not operating
properly.
Disconnect
fuel line and verify fuel delivery.
If
needed replace
pump.
Visually
check
the
linkage. Tighten/replace linkage.
Verify
by
operating
the
engine
with
clean fuel
from
a
temporary tank.
Check
for
presence
of
gasoline. Drain
and
flush
fuel supply tanks. Replace fuel/water separator
filter.
Visually
check
fuel delivery
with
an
externally connected
injector
to
one
of the
pump outlets. Replace
the
pump
if
fuel
is
not being delivered.
Check/time
the
pump (refer
to
Group
14,
Fuel
System).
Adjust
valves.
Check/replace
bad improperly operating injectors.
ENGINE
STARTS,
BUT
WILL
NOT
KEEP
RUNNING
Idle speed
too low
for
the,
accessories.
Intake
air or
exhaust system
restricted.
Air
in the
fuel
system or the
fuel
supply
is
inadequate.
Fuel
waxing due to extremely
cold
weather.
Contaminated fuel.
Adjust
the
idle
speed.
Visually
check
for
exhaust restriction and inspect
the air
intake.
Repair/replace
restricting parts.
Check
the
flow through
the
filter
and bleed
the
system.
Locate
and eliminate
the air
source.
Verify
by
inspecting
the
fuel
filter.
Clean
the
system and use
climatized fuel. Replace fuel/water separator
filter.
Check
fuel
heater
for
proper operation.
Verify
by
operating
the
engine
with
clean fuel
from
a
temporary
supply
tank.
Check
for
presence
of
gasoline. Replace fuel/water
separator
filter.
SURGING
(SPEED
CHANGE)
If
the
condition
occurs
at
idle,
the idle speed
is
set
too low for
the
accessories.
High
pressure
fuel leak.
One
or
more injectors worn
or
not operating properly.
Improperly operating injection
pump.
Adjust
the
idle.
Inspect/correct
leaks
in the
high
pressure
lines.
Fittings
and
delivery valve sealing
washers.
Check/replace
the
inoperative injectors.
Replace
the
injection pump.
ROUGH
IDLE
(IRREGULARLY
FIRING
OR
ENGINE SHAKING)
Cold
engine.
Idle speed
too low for the
accessories.
Engine
mounts damaged
or
loose.
Refer
to
troubleshooting logic
for
intake manifold heater system
(see
Group 11,
Exhaust
System
&
Intake
Manifold)
Adjust
idle
speed.
Repair
or
replace mounts.
J9109-233
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