C-12 Generator Set Engine Caterpillar

Note: If the symptom is intermittent and the symptom cannot be repeated, refer to Troubleshooting, "Intermittent Low Power or Power Cutout". If the symptom is consistent and the symptom can be repeated, continue with this procedure.

Probable Causes

• Diagnostic codes

• Electrical connectors

• Cold mode

• Throttle signal

• Unit injectors

• Fuel supply

• Air inlet and exhaust system

Recommended Actions

Note: If the symptom only occurs under certain operating conditions (high idle, full load, engine operating temperature, etc), test the engine under those conditions. Troubleshooting the symptom under other conditions can give misleading results.

Diagnostic Codes

Check for active diagnostic codes on the Caterpillar Electronic Technician (ET). Troubleshoot any active codes before continuing with this procedure.

Electrical Connectors

Check for correct installation of the J1/P1 and J2/P2 Electronic Control Module (ECM) connectors and the unit injector connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect".

Cold Mode

Use Cat ET to verify that the engine has exited cold mode. Cold mode operation may cause the engine to run rough and the engine power may be limited.

Throttle Signal

Monitor throttle signal on Cat ET. Verify that the throttle signal is stable from the low idle position to the high idle position.

Unit Injectors

1. Use Cat ET to determine if there are any active diagnostic codes for the unit injectors.

2. Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.

3. Perform the "Cylinder Cutout Test" on Cat ET in order to identify any misfiring cylinder(s). Refer to Troubleshooting, "Injector Solenoid Circuit - Test" for more information.

Fuel Supply

1. 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.

2. Check the fuel tank for foreign objects which may block the fuel supply.

3. 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

4. Cold weather adversely affects the characteristics of the fuel.

5. Check the fuel pressure during engine cranking. Check the fuel pressure after the fuel filter. 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.

Air Inlet and Exhaust System

1. Check for an air filter restriction. Clean plugged air filters or replace plugged air filters.

2. Check the air inlet and exhaust system for restrictions and/or leaks.