Service Diagnosis-Performance - Jeep cherokee 2000 Service Manual

XJ
DIAGNOSIS AND TESTING (Continued)
SERVICE DIAGNOSIS—PERFORMANCE
CONDITION
ENGINE WILL NOT CRANK
ENGINE CRANKS BUT WILL NOT
START
ENGINE LOSS OF POWER
ENGINE PERFORMANCE DIAGNOSIS CHART
POSSIBLE CAUSES
1. Weak or dead battery
2. Corroded or loose battery
connections
3. Faulty starter or related circuit(s)
4. Siezed accessory drive
component
5. Engine internal mechanical
failure or hydro-static lock
1. No spark
2. No fuel
3. Low or no engine compression
1. Worn or burned distributor rotor
2. Worn distributor shaft
3. Worn or incorrect gapped spark
plugs
4. Dirt or water in fuel system
5. Faulty fuel pump
6. Incorrect valve timing
7. Blown cylinder head gasket
8. Low compression
9. Burned, warped, or pitted valves
10. Plugged or restricted exhaust
system
11. Faulty ignition cables
4.0L ENGINE
CORRECTION
1. Charge/Replace Battery. Refer to
Group 8A, Battery, for correct
procedures. Check charging system.
Refer to Group 8C, Charging
Systems, for correct procedures.
2. Clean/tighten suspect battery/
starter connections
3. Check starting system. Refer to
Group 8B, Starting Systems, for
correct diagnostics/procedures
4. Remove accessory drive belt and
attempt to start engine. If engine
starts, repair/replace siezed
component.
5. Refer to Group 9, Engine, for
correct diagnostics/procedures
1. Check for spark. Refer to Group
8D, Ignition System, for correct
procedures.
2. Perform fuel pressure test, and if
necessary, inspect fuel injector(s)
and driver circuits. Refer to Group
14, Fuel System, for correct
procedures.
3. Perform cylinder compression
pressure test. Refer to Group 9,
Engine, for correct procedures.
1. Install new distributor rotor
2. Remove and repair distributor
(Refer to group 8D, Ignition System
3. Clean plugs and set gap. (Refer
to group 8D, Ignition System)
4. Clean system and replace fuel
filter
5. Install new fuel pump
6. Correct valve timing
7. Install new cylinder head gasket
8. Test cylinder compression
9. Install/Reface valves as
necessary
10. Install new parts as necessary
11. Replace any cracked or shorted
cables
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