Engine Cranks but Does Not Start
- Diagnostic codes
- Event codes
- Electrical power supply to the Electronic Control Module (ECM)
- Engine shutdown switches (if applicable)
- Engine speed/timing
- Low-pressure fuel system
- Unit injectors
- Fuel Quality
- Gear train
Note: If Cat ET will not communicate with the ECM, the problem is most likely with the electrical power supply to the ECM. Refer to Troubleshooting, "Electrical Power Supply - Test"
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| Troubleshooting Test Steps | Values | Results |
1. Diagnostic Codes, Event Codes, and Electrical Power Supply to the ECM A. Certain diagnostic codes and/or event codes may prevent the engine from starting. Connect Caterpillar Electronic Technician (ET) and check for active codes and/or for logged codes. Troubleshoot any codes that are present before continuing with this procedure. NOTE: Upon initial cranking, the status for engine speed may indicate that the engine speed signal is abnormal. This message will be replaced with an engine speed once the ECM is able to calculate a speed from the signal. |
Codes |
Result: No codes are active or logged. Proceed to Test Step 2. Result: Codes are active or logged. Use the appropriate circuit test to troubleshoot any active diagnostic codes before continuing with this procedure. |
2. Engine Shutdown Switches (If Applicable) A. The engine shutdown switches must be in the OFF position. B. Use Cat ET to verify the status of the engine shutdown switches. When a shutdown occurs, the keyswitch must be turned to the OFF position for at least 15 seconds before restarting the engine. |
Shutdown switches |
Result: The switches are in the OFF position. Proceed to Test Step 3. Result: The switches are not in the OFF position. Turn the switches to the OFF position. |
3. Engine Speed/Timing A. Crank the engine and observe the engine speed on the Cat ET status screen. If Cat ET indicates 0 rpm, refer to Troubleshooting, "Speed/Timing - Test" |
Timing signal |
Result: The timing sensor is operating properly. Proceed to Test Step 4. Result: The timing sensor is not operating properly. Refer to Troubleshooting, "Speed/Timing - Test" for troubleshooting information. |
4. Low Pressure Fuel System A. Inspect the fuel system. Refer to Systems Operation/ Testing and Adjusting, "Fuel System" for additional information. B. Check the filtered fuel pressure while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for the test procedure and for the correct pressure values. C. Check for the proper operation of the fuel transfer pump. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for test information. |
Fuel system |
Result: The fuel system pressure is OK. Proceed to Test Step 5. Result: The fuel system pressure is NOT OK. If the fuel pressure is low, replace the fuel filters. Clean the primary filter/water separator of debris. Refer to the Operation and Maintenance Manual for details. Continue with this procedure, if the problem is not resolved. |
5. Unit Injectors A. Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM. Refer to Troubleshooting, "Injector Solenoid - Test" for additional information. |
Injectors |
Result: The unit injectors are operating properly. Proceed to Test Step 6. Result: The unit injectors are NOT operating properly. Isolate the misfiring injector. Make the necessary repairs. Verify that the problem is resolved. |
6. Fuel Quality A. Obtain a fuel analysis. Cold weather adversely affects the characteristics of the fuel. Refer to the engines Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation. |
Fuel |
Result: The fuel quality is OK. Proceed to Test Step 7. Result: The fuel quality is Not OK. Drain the fuel. Replace the fuel. For further information, refer to the engine Operation and Maintenance Manual. |
7. Gear Train A. Verify that the crankshaft and the camshaft drive gears are set with the proper orientation for engine timing. B. Check the gear train for excessive wear. |
Timing and Wear |
Result: The crankshaft and the camshaft are in time. The gear train is OK. Result: The crankshaft and the camshaft drive gears are not in time. Refer to the Disassembly and Assembly manual for more information. The gear train has excessive wear. Refer to the Reuse and Salvage Guidelines manual. |
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