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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 113 (Engine Controls And Fuel - 4.3L (LV1) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Fuel System Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

Fuel Pressure Low

  1. Verify none of the conditions listed below exist:
    • Restricted or dislocated fuel feed front pipe check valve
    • Restricted fuel feed pipe
    • Poor connections at the fuel pump harness connector and the ground circuits.
    • If a condition exists 

      Repair as necessary.

    • Go to next step: If no conditions exist 
  2. Replace the G12 Fuel Pump.

Fuel Pressure Leaks Down

  1. Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief .
  2. Install the CH - 37287 - 1A  between the fuel feed pipe and the fuel rail.
  3. Open both valves on the CH - 37287 - 1A  .
  4. Ignition ON, command the Fuel Pump Enable ON with a scan tool.
  5. Close one of the valves on the CH - 37287 - 1A  .
  6. Verify that the Fuel Pressure Sensor parameter does not decrease greater than 34 kPa (5 PSI) in 1 minute.
    • If greater than 34 kPa (5 PSI) 

      Test or replace the G12 Fuel Pump.

    • Go to next step: If less than 34 kPa (5 PSI) 
  7. Test for a faulty fuel feed front pipe check valve.
    • If a condition exists 

      Replace the fuel feed front pipe.

    • Go to next step: If no condition exists 
  8. Test for a leaking G18 High Pressure Fuel Pump.
    • If a condition exists 

      Replace the G18 High Pressure Fuel Pump.

    • Go to next step: If no condition exists 

      Go to next step: Locate and replace the leaking Q17 Fuel Injector.

Fuel Pressure Drops OFF

  1. Verify none of the conditions listed below exist:
    • Restricted or dislocated fuel feed front pipe check valve
    • Restricted fuel feed pipe
    • Poor connections at the fuel pump harness connector and the ground circuits.
    • If a condition exists 

      Repair as necessary.

    • Go to next step: If no conditions exist 
  2. Replace the G12 Fuel Pump.
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