- Fuel position multiplier (if applicable)
- Engine speed/timing sensor(s)
- Turbocharger
- Rated fuel position
- Air inlet and exhaust restrictions
- Derates
- Throttle signal
- Power supply for the Electronic Control Module (ECM)
- Fuel supply
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.
Fuel Position Multiplier (if applicable)
If equipped, use Caterpillar Electronic Technician (ET) to verify that the fuel position multiplier is not affecting the available fuel rack. Refer to the diagnostic procedure Troubleshooting, "Fuel Position Multiplier".
Check Cat ET for a 190-08 diagnostic code that has been logged for the primary engine speed/timing sensor. If the engine is equipped with a secondary engine speed/timing sensor, check for a 342-08 diagnostic code that has been logged for the secondary engine speed/timing sensor. Refer to the diagnostic functional test Troubleshooting, "Engine Speed/Timing Sensor".
Ensure that the turbocharger is operating correctly. Periodic inspection and cleaning is recommended for the turbocharger compressor housing (inlet side).
Operate the engine under full load. Use Cat ET in order to monitor the following values: turbocharger compressor outlet pressure, fuel position, rated fuel position and Fuel Ratio Control (FRC). The fuel position should equal the rated fuel position. The FRC fuel position should be greater than the rated fuel position.
If any of the above values are changing rapidly for no apparent reason, there may be an intermittent problem with the wiring. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".
Air Inlet and Exhaust Restrictions
Check the air inlet system for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines.
Check for an air filter restriction indicator. Replace plugged air filters and/or clean filters. Repair any leaks.
Use Cat ET in order to monitor the status of the throttle. Observe the throttle position. Verify that the throttle position is smooth from low idle to high idle. The throttle position should reach 100 percent at high idle.
- Inspect the circuit between the ECM and the batteries. Refer to the Electrical System Schematic. Inspect the wires, the connectors, and the components in the circuit. Refer to Troubleshooting, "Electrical Power Supply" for more information.
- Inspect the circuit between the ECM and the keyswitch. Refer to the Electrical System Schematic. Inspect the wires, the connectors, and the components in the circuit. Refer to Troubleshooting, "Electrical Power Supply" for more information.
- 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.
- 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
Refer to the Operation and Maintenance Manual for the correct procedure.
Note: A sight glass in the fuel supply line is helpful in diagnosing air in the fuel.
- 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.
- Check the fuel pressure after the fuel filter while the engine is being cranked. Refer to the Systems Operation/Testing and Adjusting manual 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 Systems Operation/Testing and Adjusting for more information.