3126B Petroleum Engine Caterpillar

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The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.

Note: Use this procedure only if the engine does not shut down completely.

Probable Causes

• Diagnostic codes

• Event codes

• Throttle signal

• Electrical connectors

• Fuel supply

• Injection actuation pressure

Recommended Actions

Diagnostic Codes and Event Codes

Certain diagnostic codes and/or event codes may cause poor performance. Connect the Caterpillar Electronic Technician (ET) and check for active codes and for logged codes. Troubleshoot any codes that are present before continuing with this procedure.

Throttle Signal

View the status for the throttle position on the status screen. Operate the throttle from the low idle position to the high idle position. The status should be approximately 0 percent at low idle and the status should be approximately 100 percent at high idle. Refer to Troubleshooting, "Throttle Position Sensor - Calibrate" if either value is incorrect.

Diagnostic codes that are related to the J1939 data link will prevent correct operation of the throttle if the throttle position is transmitted over the data link. If there is a problem with the data link, the engine will remain at low idle until the data link is repaired.

Electrical Connectors

1. Inspect the battery wires from the Electronic Control Module (ECM) back to the battery compartment. Refer to the Electrical System Schematic. Inspect the wires and the power relay. Check the power and the ground connections to the ECM. Refer to Troubleshooting, "Electrical Power Supply Circuit - Test" for more information.

Fuel Supply

1. Check the fuel level.

2. Monitor the exhaust for smoke while the engine is being cranked.

   If no smoke is present, there may be a problem with the fuel quality or there may be a problem with the fuel supply.

3. Check the fuel pressure. Refer to Systems Operation/Testing and Adjusting, "Fuel System Pressure - Test".

4. Ensure that the fuel system has been primed. Refer to Operation and Maintenance Manual, "Fuel System - Prime".

5. Check for fuel supply lines that are restricted.

6. Check the fuel filters.

7. Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.

Injection Actuation Pressure

1. Use Cat ET to check the injection actuation pressure.

   1. Crank the engine and monitor the injection actuation pressure.

   2. Monitor the output of the injection actuation pressure control valve.

      The high pressure oil system is operating properly if the pressure output is a minimum of 6 MPa (875 psi).

2. Check for a 164-11 Injection Actuation Pressure system fault. If the diagnostic code has been logged recently, refer to Troubleshooting, "Injection Actuation Pressure Control Valve Circuit - Test".

3. If higher than actual pressure is indicated, disconnect the injection actuation pressure sensor and try to start the engine. If the engine starts, refer to Troubleshooting, "Injector Actuation Pressure Sensor -Test".