RETAINER 4491750 - Caterpillar

Probable Causes
Unit injectors
Fuel supply
Air shutoff valves (if applicable) or blocked air supply
Low engine idle
Accessory equipmentRecommended Actions
Unit Injectors
Check for correct installation of the J1/P1 and J2/P2 connectors for the Electronic Control Module (ECM). Check for correct installation of the connectors for the unit injectors. Refer to Troubleshooting, "Inspecting Electrical Connectors".
Perform the "Injector Solenoid Test" with the Caterpillar Electronic Technician (ET) in order to determine if all of the injector solenoids are being energized by the ECM.
Perform the "Cylinder Cutout Test" with Cat ET in order to identify any injectors that might be misfiring. Refer to Troubleshooting, "Injector Solenoids" for the proper procedure. Fuel Supply
Check the fuel pressure. Refer to the Systems Operation/Testing and Adjusting manual for the correct procedure.
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.
Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
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 injectorsNote: 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 applicable 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. Air Shutoff Valves (if applicable)
Verify that the air shutoff valves are open.
Check for restrictions in the air inlet system. Refer to the Systems Operation/Testing and Adjusting manual for information on the air inlet system. Low Idle
Check the low idle setting.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.