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Home >> Chevrolet >> 2022 >> Tahoe PPV, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (5 Of 5)) >> Diagnostic Information and Procedures >> Fuel System Diagnosis - High Pressure Side >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.

Test 1

  1. Ignition/Vehicle - Off
    2. NOTE:
    • In order to perform step 2 - 5, the fuel temperature must be greater than 10°C (50°F) or misdiagnosis may occur.
    • Leave the electrical connector connected.
  2. Disconnect the component: Fuel Return Hose @ Q18B Fuel Pressure Regulator 2 & Plug the fuel return hose(s) in order to prevent leakage.
  3. Install suitable hose to the component: Outlet @ Q18B Fuel Pressure Regulator 2 & Place the other end of the hose into a suitable container.
  4. Engine - Cranking - Until air is purged from the hose
  5. Engine - Cranking - For 15 s

    Verify the container contains less than 15 mL (0.5 US fl oz)

    • If 15 mL (0.5 US fl oz) or greater 

      Replace the component: Q18B Fuel Pressure Regulator 2

    • Go to next step: If less than 15 mL (0.5 US fl oz) 
  6. Ignition/Vehicle - Off
  7. Install the component: Fuel Return Hose @ Q18B Fuel Pressure Regulator 2
  8. Disconnect the electrical connector: Q17 Fuel Injector - All
  9. Disconnect the component: Fuel Injection Fuel Return Pipe @ Q17 Fuel Injector - All - Refer to: Fuel Injector Fuel Return Pipe Replacement

    Plug the fuel return hose(s) in order to prevent leakage. @ Diesel Fuel Separator & Fuel Rail

  10. Engine - Cranking - For 15 s
  11. Verify the condition does not exist: Leaking @ Q17 Fuel Injector
    • If a condition exists 

      Replace the appropriate component: Q17 Fuel Injector

    • Go to next step: If no condition exists 
  12. Ignition/Vehicle - Off
  13. Install the component: Fuel Injection Fuel Return Pipe
    14. NOTE:

    Perform the following test for all 6 components. - One at a time

  14. Perform the following steps:
    1. Disconnect the electrical connector: Q17 Fuel Injector - All
    2. Remove the component: F5BA Fuse @ X50B Fuse Block - Underhood Auxiliary
    3. Disconnect the electrical connector: E12 Glow Plug
      4. NOTE:

      The component must be discarded whenever removed and replaced with a NEW component:

    4. Remove the component: E12 Glow Plug - One at a time
    5. Place and hold a clean shop towel over the component: Threaded Hole @ Cylinder Head - Glow Plug
    6. Engine - Cranking - For 6 s

      Verify the condition does not exist: Fuel @ Shop Towel

    • If a condition exists 

      Replace the appropriate component: Q17 Fuel Injector

    • Go to next step: If no condition exists 
  15. Test or replace the component: G18 Fuel Pump - High Pressure

Test 2

  1. Engine - Idling
  2. Perform the following procedure/test: Cylinder Power Balance Test 

    Verify the procedure/test passes.

    • If the procedure/test does not pass 

      Replace the component that failed the test: Q17 Fuel Injector

    • Go to next step: If the procedure/test passes 
  3. Ignition/Vehicle - Off
    4. NOTE:
    • In order to perform step 4 - 7, the fuel temperature must be greater than 10°C (50°F) or misdiagnosis may occur.
    • Leave the electrical connector connected.
  4. Disconnect the component: Fuel Return Hose @ Q18B Fuel Pressure Regulator 2 & Plug the fuel return hose(s) in order to prevent leakage.
  5. Install suitable hose to the component: Outlet @ Q18B Fuel Pressure Regulator 2 & Place the other end of the hose into a suitable container.
  6. Engine - Idling - Until air is purged from the hose
  7. Engine - Idling - For 15 s

    Verify the container contains less than 15 mL (0.5 US fl oz)

    • If 15 mL (0.5 US fl oz) or greater 

      Replace the component: Q18B Fuel Pressure Regulator 2

    • Go to next step: If less than 15 mL (0.5 US fl oz) 
  8. Ignition/Vehicle - Off
  9. Install the component: Fuel Return Hose @ Q18B Fuel Pressure Regulator 2
  10. Disconnect the electrical connector: Q17 Fuel Injector - All
  11. Disconnect the component: Fuel Injection Fuel Return Pipe @ Q17 Fuel Injector - All - Refer to: Fuel Injector Fuel Return Pipe Replacement

    Plug the fuel return hose(s) in order to prevent leakage. @ Diesel Fuel Separator & Fuel Rail

  12. Engine - Cranking - For 15 s
  13. Verify the condition does not exist: Leaking @ Q17 Fuel Injector
    • If a condition exists 

      Replace the appropriate component: Q17 Fuel Injector

    • Go to next step: If no condition exists 
  14. Ignition/Vehicle - Off
  15. Install the component: Fuel Injection Fuel Return Pipe
    16. NOTE:

    Perform the following test for all 6 components. - One at a time

  16. Perform the following steps:
    1. Disconnect the electrical connector: Q17 Fuel Injector - All
    2. Remove the component: F5BA Fuse @ X50B Fuse Block - Underhood Auxiliary
    3. Disconnect the electrical connector: E12 Glow Plug
      4. NOTE:

      The component must be discarded whenever removed and replaced with a NEW component:

    4. Remove the component: E12 Glow Plug - One at a time
    5. Place and hold a clean shop towel over the component: Threaded Hole @ Cylinder Head - Glow Plug
    6. Engine - Cranking - For 6 s

      Verify the condition does not exist: Fuel @ Shop Towel

    • If a condition exists 

      Replace the appropriate component: Q17 Fuel Injector

    • Go to next step: If no condition exists 
  17. Test or replace the component: G18 Fuel Pump - High Pressure
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