Jeep Cherokee

 Service Manual

Engine » 2.5L engine » Diagnosis and testing
Service diagnosis-performance

CONDITION

POSSIBLE CAUSES

CORRECTION

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.  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. No spark
2.  No fuel
3.  Low or no engine compression

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. 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
12. Faulty ignition coil

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
12. Test and replace, as necessary (Refer to Group 8D, ignition system)

1. Carbon build-up on throttle plate
2. Engine idle speed too low
3. Worn or incorrectly gapped spark plugs
4. Worn or burned distributor rotor
5. Spark plug cables defective or crossed
6. Faulty coil (Refer to group 8D, Ignition System)
7. Intake manifold vacuum leak
8. EGR valve leaking or stuck open

1.  Remove throttle body and de-carbon. (Refer to Group 14 for correct procedures)
2. Check Idle Air Control circuit. (Refer to Group 14, Fuel System)
3.  Replace or clean and re-gap spark plugs (Refer to group 8D, Ignition System)
4. Install new distributor rotor
5.  Check for correct firing order or replace spark plug cables. (Refer to Group 8D, Ignition System for correct procedures.)
6. Test and replace, if necessary
7.  Inspect intake manifold gasket and vacuum hoses. Replace if necessary (Refer to Group 11, Exhaust System & Intake Manifold)
8. Test and replace, if necessary (Refer to group 25, Emission Control Systems)

1. Worn or incorrectly gapped spark plugs
2.  Spark plug cables defective or crossed
3. Dirt in fuel system
4.  Burned, warped or pitted valves
5. Faulty coil

1. Replace spark plugs or clean and set gap. (Refer to group 8D, Ignition System)
2. Check Idle Air Control circuit. (Refer to Group 14, Fuel System)
3. Clean fuel system
4.  Install new valves
5. Test and replace as necessary (refer to group 8D, Ignition System)