HUB AS 6Y5985 - Caterpillar

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
Engine operation
Fuel supply
Fuel quality
Engine speed/timing
Unit injectors
Air inlet and exhaust system
Accessory equipmentRecommended Actions
Engine Operation
Use Caterpillar Electronic Technician (ET) to check the "Current Totals" for excessive idle time and/or for a high load factor which would be indicative of poor operating habits.Note: Engine operation may also be affected by environmental conditions such as wind and snow.Fuel Supply
Check the fuel level in the fuel tank. Ensure that adequate fuel is available for the application.Check fuel lines for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines.
Check the fuel tank for foreign objects which may block the fuel supply. Check for air leaks in the suction line of the fuel pump. Prime the fuel system after you perform the following procedures:
Replacing the fuel filters
Working on the low pressure fuel supply circuit
Replacing fuel injectors
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 operation. 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. Fuel Quality
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.Engine Speed/Timing
Perform a speed/timing sensor calibration. Refer to Troubleshooting, "Timing - Calibrate".Unit Injectors
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".
Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
Perform the "Cylinder Cutout Test" on Cat ET in order to identify any injectors that might be misfiring. Refer to Troubleshooting, "Injector Solenoid - Test". Air Inlet and Exhaust System
Inspect the air filter for a restriction. If the air filter shows signs of being plugged, clean the air filter or replace the air filter.
Check the air inlet and exhaust system for restrictions and/or for leaks. Refer to Systems Operation/Testing and Adjusting. 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.