1988 JEEP CHEROKEE 6 cylinder

batteries
Bad starter connections Check connections
or bad starter and/or replace
batteries









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Engine Cranks Bad battery connections Check connections
Slowly, Won't or dead batteries and/or replace
Start batteries
Engine oil too heavy Replace engine oil









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Engine Cranks Glow plugs not functioning Check glow plug system,
Normally, But see FUEL SYSTEMS
Will Not Start Glow plug control not Check controller, see
functioning FUEL SYSTEMS
Fuel not injected into Check fuel injectors,
cylinders see FUEL SYSTEMS
No fuel to injection pump Check fuel delivery
system
Fuel filter blocked Replace fuel filter
Fuel tank filter blocked Replace fuel tank
filter
Fuel pump not operating Check pump operation
and/or replace pump
Fuel return system blocked Inspect system and
remove restriction
No voltage to fuel solenoid Check solenoid and
connections
Incorrect or contaminated Replace fuel
fuel
Incorrect injection pump Re-adjust pump timing,
timing see FUEL SYSTEMS
Low compression Check valves, pistons,
rings, see ENGINES
Injection pump malfunction Inspect and/or replace
injection pump









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Engine Starts, Incorrect slow idle Reset idle adjustment,
Won't Idle adjustment see TUNE-UP
Fast idle solenoid Check solenoid and
malfunctioning connections
Fuel return system blocked Check system and remove
restrictions
Glow plugs go off too soon See glow plug diagnosis
in FUEL SYSTEMS
Injection pump timing Reset pump timing, see
incorrect FUEL SYSTEMS
No fuel to injection pump Check fuel delivery
system
Incorrect or contaminated Replace fuel
fuel
Low compression Check valves, piston,
rings, see ENGINES
Injection pump malfunction Replace injection pump,
see FUEL SYSTEMS
Fuel solenoid closes in RUN Check solenoid and
position connections









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Engines Starts/ Incorrect slow idle Reset slow idle, see
Idles Rough W/out adjustment TUNE-UP
Smoke or Noise Injection line fuel leaks Check lines and
connections
Fuel return system blocked Check lines and
connections

Air in fuel system Bleed air from system
Incorrect or contaminated Replace fuel
fuel
Injector nozzle malfunction Check nozzles, see
FUEL SYSTEMS









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Engines Starts Injection pump timing Reset pump timing, see
and Idles Rough incorrect FUEL SYSTEMS
W/out Smoke or Engine not fully broken in Put more miles on
Noise, But Clears engine
After Warm-Up Air in system Bleed air from system
Injector nozzle malfunction Check nozzles, see
FUEL SYSTEMS









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Engine Idles Blocked fuel filter Replace fuel filter
Correctly, Injection pump timing Reset pump timing, see
Misfires Above incorrect FUEL SYSTEMS
Idle Incorrect or contaminated Replace fuel
fuel









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Engine Won't Fast idle adjustment Reset fast idle, see
Return To Idle incorrect TUNE-UP
Internal injection pump Replace injection pump,
malfunction see FUEL SYSTEMS
External linkage binding Check linkage and
remove binding









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Fuel Leaks On Loose or broken fuel line Check lines and
Ground connections
Internal injection pump Replace injection pump,
seal leak see FUEL SYSTEMS









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Cylinder Injector nozzles sticking Test injectors, see
Knocking Noise open FUEL SYSTEMS
Very low nozzle opening Test injectors and/or
pressure replace









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Loss of Engine Restricted air intake Remove restriction
Power EGR valve malfunction Replace EGR valve
Blocked or damaged exhaust Remove restriction
system and/or replace
components
Blocked fuel tank filter Replace filter
Restricted fuel filter Remove restriction
and/or replace filter
Block vent in gas cap Remove restriction
and/or replace cap
Tank-to-injection pump fuel Check fuel lines and
supply blocked connections
Blocked fuel return system Remove restriction
Incorrect or contaminated Replace fuel
fuel
Blocked injector nozzles Check nozzle for
blockage, see FUEL
SYSTEMS
Low compression Check valves, rings,
pistons, see ENGINES









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Loud Engine Basic timing incorrect Reset timing, see
Noise With Black FUEL SYSTEMS
Smoke EGR valve malfunction Replace EGR valve
Internal injection pump Replace injection pump,
malfunction see FUEL SYSTEMS

Excessive cylinder wear Rebore or replace
block
Excessive valve guide Worn or loose bearing
clearance









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Gap Bridged Deposits in combustion Clean combustion
chamber becoming fused chamber of deposits
to electrode









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Blistered Engine overheating Check cooling system
Electrode
Wrong type of fuel Replace with correct
fuel
Loose spark plugs Retighten spark plugs
Over-advanced ignition Reset ignition timing
timing see ENGINE PERFORMANCE









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Pre-Ignition or Incorrect type of fuel Replace with correct
Melted Electrodes fuel
Incorrect ignition timing Reset ignition timing
see ENGINE PERFORMANCE
Burned valves Replace valves
Engine Overheating Check cooling system
Wrong type of spark plug, Replace with correct
too hot spark plug, see
ENGINE PERFORMANCE









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Chipped Severe detonation Check for over-
Insulators advanced timing or
combustion
Improper gapping Re-gap spark plugs
procedure









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Rust Colored Additives in unleaded Try different fuel
Deposits fuel brand









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Water In Combus- Blown head gasket or Repair or replace
tion Chamber cracked head head or head gasket









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NOTE: Before diagnosing an electronic ignition system, ensure that
all wiring is connected properly between distributor, wiring
connector and spark plugs. Ignition problem will show up
either as: Engine Will Not Start or Engine Runs Rough.
BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS









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CONDITION POSSIBLE CAUSE CORRECTION








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Engine Won't Open circuit between Repair circuit
Start distributor and bulkhead
connector
Open circuit between Repair circuit
bulkhead connector and

repair








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One or More, But Carburetor idle mixture Readjust carburetor,
Not All Firing not balanced see ENGINE PERFORMANCE
Voltage Lines are
Higher Than Others EGR valve stuck open Clean and/or replace
valve
High resistance in spark Replace spark plug
plug wires wires
Cracked or broken spark Replace spark plugs
plug insulator
Intake vacuum leak Repair leak
Defective spark plugs Replace spark plugs
Corroded spark plug Replace spark plugs
terminals









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One or More, But Curb idle mixture not Readjust carburetor,
Not All Firing balanced see ENGINE PERFORMANCE
Voltage Lines Are
Lower Than Others Breaks in plug wires Replace plug wires
causing arcing
Cracked coil tower causing Replace coil
arcing
Low compression Determine cause and
repair
Defective spark plugs Replace spark plugs
Corroded spark plugs Replace spark plugs









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Cylinders Not Cracked distributor cap Replace distributor
Firing terminals cap
Shorted spark plug wire Determine cause and
repair
Mechanical problem in Determine cause and
engine repair
Defective spark plugs Replace spark plugs
Spark plugs fouled Replace spark plugs









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BASIC DRIVEABILITY PROBLEMS TROUBLE SHOOTING TABLE








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CONDITION POSSIBLE CAUSE CORRECTION








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Hard Starting Binding carburetor linkage Eliminate binding
Binding choke linkage Eliminate binding
Binding choke piston Eliminate binding
Restricted choke vacuum Check vacuum lines
for blockage

Defective clutch master Replace master cylinder
Defective clutch slave Replace slave cylinder
Air in hydraulic system Bleed hydraulic system









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Rattling Weak or broken release Replace spring and
lever spring check alignment
Damaged pressure plate Replace pressure plate
Broken clutch return spring Replace return spring
Worn splines on clutch disc Replace clutch disc
or input shaft and/or input shaft
Worn clutch release bearing Replace release bearing
Dry or worn pilot bearing Lubricate or replace
pilot bearing
Unequal release lever Align or replace
contact release lever
Incorrect pedal free play Adjust free play
Warped or damaged clutch Replace damaged
disc components









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Slipping Pressure springs worn or Release pressure plate
Oily, greasy or worn Clean or replace clutch
facings disc
Incorrect clutch alignment Realign clutch assembly
Warped clutch disc or Replace damaged
pressure plate components
Binding release levers or Lubricate and/or
clutch pedal replace release
components









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Squeaking Worn or damaged release Replace release bearing
Dry or worn pilot or Lubricate or replace
release bearing assembly
Pilot bearing turning in Replace pilot bearing
crankshaft and/or crankshaft
Worn input shaft bearing Replace bearing and
seal
Incorrect transmission Realign transmission
alignment
Dry release fork between Lubricate release fork
pivot and pivot









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Heavy and/or Sticking release bearing Replace release bearing
Stiff Pedal sleeve and/or sleeve

Dry or binding clutch Lubricate and align
pedal hub components
Floor mat interference Lay mat flat in proper
with pedal area
Dry or binding ball/fork Lubricate and align
pivots components
Faulty clutch cable Replace clutch cable









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Noisy Clutch Faulty interlock switch Replace interlock
Pedal switch
Self-adjuster ratchet Lubricate or replace
noise self-adjuster
Speed control interlock Lubricate or replace
switch interlock switch









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Clutch Pedal Binding clutch cable See CLUTCH article
Sticks Down
Springs weak in pressure Replace pressure plate
plate
Binding in clutch linkage Lubricate and free
linkage









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Noisy Dry release bearing Lubricate or replace
release bearing
Dry or worn pilot bearing Lubricate or replace
bearing
Worn input shaft bearing Replace bearing









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Transmission Weak springs in pressure Replace pressure plate
Click plate
Release fork loose on ball Replace release fork
stud and/or ball stud
Oil on clutch disc damper Replace clutch disc
Broken spring in slave Replace slave cylinder
cylinder









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DRIVE AXLE - NOISE DIAGNOSIS
Unrelated Noises
Some driveline trouble symptoms are also common to the
engine, transmission, wheel bearings, tires, and other parts of the
vehicle. Ensure cause of trouble actually is in the drive axle before
adjusting, repairing, or replacing any of its parts.
Non-Drive Axle Noises
A few conditions can sound just like drive axle noise and
have to be considered in pre-diagnosis. The 4 most common noises are
exhaust, tires, CV/universal joints and wheel trim rings.

Free play in steering See STEERING COLUMN
shaft bearing article
Bearing loose on shaft See STEERING COLUMN
serrations article









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Clicking Noise Pump slippers too long See POWER STEERING PUMP
in Pump article
Broken slipper springs See POWER STEERING PUMP
article
Excessive wear or nicked See POWER STEERING PUMP
rotors article
Damaged cam contour See POWER STEERING PUMP
article









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Poor Return of Wheel rubbing against See STEERING COLUMN
Wheel turn signal SWITCHES article
Flange rubbing steering See STEERING COLUMN
gear adjuster article
Tight or frozen steering See STEERING COLUMN
shaft bearing article
Steering gear out of See POWER STEERING GEAR
adjustment article
Sticking or plugged See POWER STEERING PUMP
spool valve article
Improper front end See WHEEL ALIGNMENT
alignment article
Wheel bearings worn or See FRONT SUSPENSION
loose article
Ties rods or ball joints Check and replace if
binding necessary
Intermediate shaft joints See STEERING COLUMN
binding article
Kinked pressure hoses Correct or replace if
necessary
Loose housing head See POWER STEERING GEAR
spanner nut article
Damaged valve lever See POWER STEERING GEAR
article
Sector shaft adjusted See ADJUSTMENTS in POWER
too tight STEERING GEAR article
Worm thrust bearing See ADJUSTMENTS in POWER
adjusted too tight STEERING GEAR article
Reaction ring sticking See POWER STEERING GEAR
in cylinder article

Free play in pot coupling See POWER STEERING PUMP
article
Steering gear coupling See POWER STEERING PUMP
loose on shaft article
Steering disc mounting Tighten or replace if
bolts loose necessary
Coupling loose on worm Tighten or replace if
shaft necessary
Improper sector shaft See POWER STEERING GEAR
adjustment article
Excessive worm piston See POWER STEERING GEAR
side play article
Damaged valve lever See POWER STEERING GEAR
article
Universal joint loose Tighten or replace if
necessary
Defective rotary valve See POWER STEERING GEAR
article









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No Power When Sticking flow control See POWER STEERING PUMP
Parking valve article
Insufficient pump See POWER STEERING PUMP
pressure output article
Excessive internal pump See POWER STEERING PUMP
leakage article
Excessive internal gear See POWER STEERING PUMP
leakage article
Flange rubs against gear See STEERING COLUMN
adjust plug article
Loose pump belt Adjust or replace if
necessary
Low fluid level Check and add proper
amount of fluid
Engine idle too low Adjust to correct
setting
Steering gear-to-column See STEERING COLUMN
misaligned article









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No Power, Left turn reaction seal See POWER STEERING GEAR
Left Turn "O" ring worn article
Left turn reaction seal See POWER STEERING GEAR
damaged/missing article
Cylinder head "O" ring See POWER STEERING PUMP
damaged article









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