Probable Causes
- Programmable parameters
- Diagnostic codes
- Event codes
- Injector trim codes
- Starting aids
- Throttle signal
- Electrical connectors
- Unit injectors
- Fuel supply
- Boost pressure sensor
- 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.
Programmable Parameters
Verify that the complaint is not due to a normal operation such as a programmed parameter. Connect the electronic service tool and verify that the parameters are programmed correctly.
Diagnostic Codes and Event Codes
Certain diagnostic codes and/or event codes may cause poor performance. Connect the electronic service tool and check for active codes and/or logged codes. Troubleshoot any codes that are present before continuing with this procedure.
Injector Trim Codes
If any of the injectors or the electronic control module have been replaced, ensure that the injector trim codes have been reprogrammed to the correct values. Refer to Troubleshooting, "Injector Code-Calibrate".
Starting Aids
Cold Mode
Use the electronic service tool to verify that the engine has exited cold mode. If the engine is operating in cold mode, an indicator will be displayed on the top of any of the status screens on the electronic service tool. Cold mode operation may slow throttle response.
Throttle Signal
Connect the electronic service tool to the service tool connector. Turn the keyswitch to the ON position while the engine is OFF.
Monitor the throttle position from low idle to full throttle. The duty cycle should be between 5 and 10 percent at low idle. The duty cycle will increase to 90 to 95 percent at full throttle. Refer to Troubleshooting, "Speed Control - Test" for additional information if the change in the throttle position is erratic or if the change in the throttle position is out of the specified range.
Electrical Connectors
Check the J1/P1 Electronic Control Module (ECM) connector, the J2/P2 ECM connector, the J300/P300 unit injector connector, the connectors for the throttle position sensor, and the associated wiring for damage, abrasion, corrosion, or incorrect attachment. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information.
Unit Injectors
- Perform the "Injector Solenoid Test" on the electronic service tool in order to determine if all of the injector solenoids are being energized by the ECM.
- Perform the "Cylinder Cutout Test" on the electronic service tool in order to identify any injectors that might be misfiring. Refer to Troubleshooting, "Injector Solenoid Circuit - Test" for the proper procedure.
Fuel Supply
- Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
- Check the fuel tank for foreign objects which may block the fuel supply.
- Check for air in the low pressure fuel supply 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
Note: A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel. Refer to Testing and Adjusting for more information.
- Replacement of the fuel filters
- Purge air from the low pressure fuel supply circuit. Refer to Operation and Maintenance Manual, "Fuel System - Prime" for the correct procedure.
| NOTICE |
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Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again. |
- Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Publication, SEBD0717, "Diesel Fuels And Your Engine".
- Check the fuel pressure after the fuel filter while the engine is being cranked. Refer to Testing and Adjusting for the correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve. Refer to Testing and Adjusting for more information.
Boost Pressure Sensor
- Monitor the status of "Fuel Position" and "Rated Fuel Limit" on the electronic service tool. If "Fuel Position" does not equal "Rated Fuel Limit", then check the boost pressure.
- Verify that there are no active diagnostic codes that are associated with the boost pressure sensor.
- Monitor the status of "Boost Pressure" for normal operation on the electronic service tool.
Air Inlet and Exhaust System
- Check for an air filter restriction. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual for additional information.
- Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Testing and Adjusting, "Air Inlet and Exhaust System" for additional information.