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.

Probable Causes

• Diagnostic codes

• Event codes

• Programmable parameters

• Cold mode

• Throttle signal

• Injection actuation pressure

• Electrical connectors

• Unit injectors

• Boost pressure sensor, rated fuel position and/or FRC fuel position

• Air inlet and exhaust system

• Fuel supply

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.

Programmable Parameters

Use Cat ET to verify that the complaint is not due to a normal operation such as a programmed parameter. Program any parameters that are configured incorrectly.

Cold Mode

The Electronic Control Module (ECM) will activate the cold mode when the coolant temperature is below 18 °C (64 °F).

When cold mode is activated, the engine's power will be limited.

Throttle Signal

Use Cat ET to 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. If the status cannot operate in the full range, refer to the calibration procedure Troubleshooting, "Throttle Position Sensor - Calibrate".

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.

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 being indicated, disconnect the injection actuation pressure sensor and try to start the engine. If the engine starts, refer to Troubleshooting, "Injection Actuation Pressure Control Valve Circuit - Test".

Electrical Connectors

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

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. Refer to Troubleshooting, "Injector Solenoid Circuit - Test" for more information.

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.

Boost Pressure Sensor, Rated Fuel Position and/or FRC Fuel Position

1. Monitor the status of "Fuel Position", "Rated Fuel Limit", and "FRC Fuel Limit" on Cat ET while the engine is operating under full load. These parameters should reflect the information below.
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   Table 1

   "Fuel Position" = "Rated Fuel Limit" and "Fuel Position" < "FRC Fuel Limit"

   If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the electronics are operating correctly. Otherwise, proceed with Step 2.

2. Monitor the status of "Boost Pressure" and of "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, "Boost Pressure" should be 0 kPa (0 psi).

Air Inlet and Exhaust System

1. Check for an air filter restriction. If necessary, service the air filter element.

2. Check for the correct operation of the turbocharger. Refer to Systems Operation/Testing and Adjusting, "Turbocharger - Test" for more information.

3. Check for air inlet restrictions and/or leaks. Check for exhaust restrictions. Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System - Inspect" for more information.

Fuel Supply

1. Check the fuel level.

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

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

4. Check for fuel supply lines that are restricted.

5. Check the fuel filters.

6. Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Operation and Maintenance Manual for details.