BODY AS.- 3473241 - Caterpillar

Probable Causes
Event Codes
Electrical Connections
Diagnostic Codes
Throttle Signal
Fuel Supply
Air Inlet and Exhaust System
Recommended Actions
Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load, and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.
Table 1
Troubleshooting Test Steps Values Results
1. Check for Active Event Codes that may Derate Engine Power
A. Certain event codes may derate engine power. Connect Caterpillar Electronic Technician (ET) and check for active codes and/or for logged codes.
Event Codes
Result: There are no active or logged event codes.
Proceed to Test Step 2.
Result: There are active or logged codes.
Repair: Troubleshoot any codes that are present before continuing with this procedure.
2. Check the Electrical Connections
A. Verify that the following connectors are installed correctly:
• Electrical connectors for the ECM
• Connectors for the wiring harness under the valve cover
• Connectors for the engine speed/timing sensors
Electrical Connections
Result: The electrical connections are OK.
Proceed to Test Step 3.
Result: The electrical connections are NOT OK.
Repair: Refer toTroubleshooting, "Electrical Connectors - Inspect" for the proper troubleshooting procedure.
3. Check for Intermittent Diagnostic Codes
A. Certain diagnostic codes may cause poor performance. Connect Cat ET and check for active codes and/or for logged codes.
Diagnostic Codes
Result: There are no diagnostic codes present.
Proceed to Test Step 4.
Result: There are diagnostic codes present.
Repair: Troubleshoot any codes that are present before continuing with this procedure.
4. Intermittent Throttle Signal
A. Monitor the status for "Throttle Position" on Cat ET. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed.
Throttle Signal
Result: The throttle signal is OK.
Proceed to Test Step 5.
Result: The throttle signal is NOT OK.
Repair: Refer to Troubleshooting, "Speed Control - Test".
5. Fuel Supply Pressure
A. Check the fuel pressure. Ensure that the fuel is stable. Refer to Systems Operation/Testing and Adjusting for the procedure to check the fuel pressure manually.
B. Visually check the fuel level.
C. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
D. Check the fuel lines for the following problems: restrictions, collapsed lines, pinched lines and loose connections.
E. Prime the fuel system if any of the following procedures have been performed:
• Replacement of the fuel filters
• Service on the low-pressure fuel supply circuit
• Replacement of unit injectors
F. Check the fuel tank for foreign objects which may block the fuel supply.
G. Check the fuel filters.
H. Check the fuel quality. Make sure that the fuel meets the requirements of Special Publication, SEBU6250, "Caterpillar Machine Fluids Recommendations".
Fuel Supply Pressure
Result: The fuel supply pressure is OK.
Proceed to Test Step 6.
Result: The fuel supply is NOT OK.
Repair: Make the necessary repair and return the unit to service.
6. Check for a Restriction in the Air Inlet and Exhaust System
A. Ensure that the turbocharger is operating correctly. Periodic inspection and cleaning are recommended for the turbocharger compressor housing (inlet side).
B. Check the air filter restriction indicator.
C. Check the air inlet and exhaust system for restrictions and/or leaks.
Restrictions
Result: There are no restrictions in the air inlet and exhaust system.
Return the