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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 94 (Engine Controls And Fuel - 2.8L (LWN) Diesel - Diagnostic Information And Procedures (3 Of 3)) >> Diagnostic Information and Procedures >> Exhaust Aftertreatment Fuel Injector Diagnosis >> Circuit/System Testing

Circuit/System Testing

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NOTE:
  • Verify that the Q67 Exhaust Aftertreatment Fuel Injector nozzle hole is not plugged with soot.
  • Do not kink the flexible fuel hose. The fuel hose is located between the injector's electrically controlled valve and the nozzle. A hose kink may cause inaccurate test results.
  1. Remove the Exhaust Aftertreatment Fuel Injector nozzle from the exhaust pipe, but leave the fuel supply line connected to the Q67 Exhaust Aftertreatment Fuel Injector control valve. Refer to Low Pressure Diesel Hydrocarbon Injector Replacement .
  2. Place the outlet nozzle into a suitable container; a piece of hose may be connected to the outlet nozzle if necessary.
  3. Engine running, verify the Q67 Exhaust Aftertreatment Fuel Injector does not leak any fuel into the container.
    • If fuel is leaking from the outlet nozzle 

      Replace the Q67 Exhaust Aftertreatment Fuel Injector.

    • Go to next step: If no fuel is leaking from the outlet nozzle 
  4. Place the outlet nozzle or rubber hose into a graduated cylinder from the J-45873  Fuel Return Volume Test Kit.
    5. NOTE:
    • Commanding the Q67 Exhaust Aftertreatment Fuel Injector Flow Test ON prior to taking flow measurements may cause a faulty injector to test good.
    • Each time the Q67 Exhaust Aftertreatment Fuel Injector Flow Test is commanded ON, the quantity of fuel that flows into the graduated cylinder must be recorded even if little or no fuel flows.
  5. Using a scan tool, select Engine Control Module, Control Functions, and then Exhaust Aftertreatment Fuel Injector Flow Test. Run the fuel flow test 3 times and record the amount of fuel that flows into the graduated cylinder for each test. Empty the graduated cylinder before running each test.
    • If no fuel flow is present on all 3 measurements 
    1. Engine OFF
    2. Disconnect the Q67 Exhaust Aftertreatment Fuel Injector fuel supply line using CH - 49736  Hydrocarbon Injector Quick Connect Release Tool. Connect a piece of hose to the fuel supply line and place the other end into a suitable container
    3. Engine cranking/running.
    4. Verify there is fuel flow from the Q67 Exhaust Aftertreatment Fuel Injector supply line.
      • If fuel flow is present, replace the Q67 Exhaust Aftertreatment Fuel Injector.
      • Go to next step: If no fuel flow is present
      1. Verify that there is no damage or blockage in any of the fuel supply line or connections.
        • If damage or blockage is found, Repair as necessary.
        • If no damage or blockage is found, replace the G12 Fuel Pump.
    • If any measurement is less than 30 mL 

      Replace the Q67 Exhaust Aftertreatment Fuel Injector.

    • If any measurement is greater than 40 mL 

      Replace the G12 Fuel Pump.

    • Go to next step: If all measurements are between 30 mL and 40 mL 
  6. All OK, Refer to Diagnostic Aids.
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