BEARING-THRUST 4W8091 - Caterpillar

Note: If the problem occurs during high engine loads then refer to Troubleshooting, "Low Power/Poor or No Response to Throttle".Probable Causes
Diagnostic codes
Event codes
Throttle signal
Boost pressure
Fuel supply
Air inlet and exhaust system
Accessory equipment
Specific conditionsRecommended Actions
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.Throttle Signal
Monitor "Throttle Position" on Caterpillar Electronic Technician (ET). Verify that you can achieve full throttle. Refer to Troubleshooting, "Speed Control - Test" for the proper troubleshooting procedure.Use Cat ET to check the operation of the low idle switch. If a problem with the switch circuit is suspected, refer to Troubleshooting, "Switch Circuits - Test".Boost Pressure
Use Cat ET to monitor the "Fuel Position" and the "Rated Fuel Limit" during engine operation. If "Fuel Position" does not equal "Rated Fuel Limit" there may be a problem with the engine's inlet air system. Check for the proper operation of the following components:
Turbocharger
Wastegate control valve (if equipped)Refer to Systems Operation/Testing and Adjusting for specific information.
Monitor the status of the boost pressure sensor on Cat ET for normal operation. Ensure that the value for boost pressure is reasonable. Ensure that the boost pressure fluctuates with the demand of the engine. 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.
Prime the 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
Refer to the Operation and Maintenance Manual manual for the 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 during engine cranking. Check the fuel pressure after the fuel filter. 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. 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.
If air shutoff valves are installed, verify that the air shutoff valves are fully opened.
Check the air inlet and exhaust system for restrictions and/or for leaks. Refer to the Systems Operation/Testing and Adjusting for information on the air inlet and exhaust system. Accessory Equipment
Check all accessory equipment for problems that may create excessive load on the engine. Repair any damaged components or replace any damaged components.