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3406E and 3456 Industrial Engines Testing and Adjusting – Electronic Unit Injector – Test

This procedure assists in identifying the cause for an injector misfiring. Perform this procedure only after performing the Cylinder Cutout Test. Refer to Troubleshooting for more information.

 

  1. Check for air in the fuel, if this procedure has not already been performed. Refer to Testing and Adjusting, “Air in Fuel – Test”.
  1. Remove the valve cover and look for broken parts. Repair any broken parts or replace any broken parts that are found. Inspect all wiring to the solenoids. Look for loose connections. Also look for frayed wires or broken wires. Ensure that the connector for the unit injector solenoid is properly connected. Perform a pull test on each of the wires. Refer to Troubleshooting, “Electrical Connectors – Inspect”. Inspect the posts of the solenoid for arcing. If arcing or evidence of arcing is found, remove the cap assembly. Refer to Disassembly and Assembly Manual, “Electronic Unit Injector – Remove”. Clean the connecting posts. Reinstall the cap assembly and tighten the solenoid nuts to a torque of 2.5 ± 0.25 N·m (22 ± 2 lb in). Refer to Disassembly and Assembly Manual, “Electronic Unit Injector – Install”.

 

  1. Check the valve lash setting for the cylinder of the suspect unit injector. Refer to Testing and Adjusting, “Engine Valve Lash – Inspect/Adjust”.

 

  1. Ensure that the bolt that holds the unit injector is tightened to the proper torque. If necessary, loosen the bolt that holds the unit injector and tighten the bolt to a torque of 50 ± 7 N·m (37 ± 5 lb ft).

 

  1. Remove the suspect unit injector and check the unit injector for signs of exposure to coolant. Refer to Disassembly and Assembly Manual, “Electronic Unit Injector – Remove”. Exposure to coolant will cause rust to form on the injector. If the unit injector shows signs of exposure to coolant, remove the injector sleeve and inspect the injector sleeve. Refer to Disassembly and Assembly Manual, “Electronic Unit Injector Sleeve – Remove”. Replace the injector sleeve if the injector sleeve is damaged. Check the unit injector for an excessive brown discoloration that extends beyond the injector tip. If excessive discoloration is found, check the quality of the fuel. Refer to Testing and Adjusting, “Fuel Quality – Test”. Replace the seals on the injector and reinstall the injector. Refer to Disassembly and Assembly Manual, “Electronic Unit Injector – Install”. Also refer to Disassembly and Assembly Manual, “Electronic Unit Injector Sleeve – Install”.

 

  1. If the problem is not resolved, replace the suspect injector with a new injector.

 

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