SCREW 3G6906 - Caterpillar

Probable Causes
Active codes and logged codes
Incorrect parameters
Air shut-off system (if applicable)
Fuel system
Fuel injectors
Engine accessories
Parasitic loadsRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in the order of the listed test steps.
Table 1
Troubleshooting Test Steps    Values    Results    
1. Check for Active Codes and Logged Codes
A. Establish communication between Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM).
B. Monitor the diagnostic codes on Cat ET. Certain diagnostic codes and/or event codes may cause poor performance.
Note: Wait at least 30 seconds in order for diagnostic codes to become active.
   
Codes
   
Result: A code is active or logged.
Repair: Troubleshoot any codes before continuing with this procedure.
Verify that the repair eliminated the problem.
Result: A code is not active or logged.
Proceed to Test Step 2.
   
2. Check for Incorrect Parameters
A. Use Cat ET to verify that the correct parameters are being used. Refer to Troubleshooting, "Configuration Parameters" for additional information.
   
Parameters
   
Result: The correct parameters are being used.
Proceed to Test Step 3.
Result: The correct parameters are not being used.
Repair: Configure the correct parameters.
Verify that the repair eliminated the problem.
   
3. Inspect the Air Shutoff System (if applicable))
A. Check for proper operation of the air shutoff system. Refer to Troubleshooting, "Air Shutoff - Test".
   
Air Shutoff
   
Result: The air shutoff is operating correctly.
Proceed to Test Step 4.
Result: The air shutoff is not operating correctly.
Repair: Make the necessary repairs.
Verify that the repair eliminated the problem.
   
4. Check the Fuel System
A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.
B. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
C.. Inspect the fuel system. Refer to Systems Operation/Testing and Adjusting, "Fuel System - Inspect" for additional information.
Cold weather adversely affects the characteristics of the fuel. Refer to the engines Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation.
D. Check fuel quality. Refer to Systems Operation/Testing and Adjusting, "Fuel Quality - Test" for the proper procedure. Check the fuel tank for debris or foreign objects which may block the fuel supply.
E. Check the filtered fuel pressure while the engine is being cranked. Refer to Troubleshooting, "Fuel Pressure Is Low" for the proper testing procedure.
   
Fuel System
   
Result: The fuel system is operating properly.
Proceed to Test Step 5.
Result: The fuel system is not operating properly.
Repair: Make the necessary repairs.
Verify that the repair eliminates the problem.
   
5. Test the Fuel Injectors
If service has been performed on the engine fuel system recently, verify that the injector trim files are correct. Use Cat ET to check that the injector trim files are correct for the injectors that are installed on the engine.
A. Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
B. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu.
C. Perform the "Automatic Cylinder Cutout Test" on Cat ET.
   
Fuel Injector
   
Result: The test was