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Home >> Chevrolet >> 2021 >> Trailblazer RS, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls And Fuel - 1.0L (L4B L4F L4G LIJ) Or 1.2L (L4H L4K LIF LIH) - 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 variant/trim than selected.

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
    • Inspect the harness connectors and the ground circuits of the fuel pump for poor connections
    • If a condition exists 

      Repair as necessary.

    • Go to next step: If no conditions exist 

      Go to next step: Replace the G12 Fuel Pump.

Fuel Pressure Leaks Down

  1. Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief .
  2. Install the EN-37287  between the chassis fuel feed hose and the engine compartment fuel feed pipe.
  3. Open the valve on the EN-37287  .
  4. Ignition ON, command the Fuel Pump Enable On and then Off with a scan tool.
  5. Close the valve on the EN-37287  .
  6. Verify that the scan tool Fuel Pressure Sensor parameter does not decrease more than 34 kPa (5 PSI) in 1 min.
    • If greater than 34 kPa (5 PSI) 

      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
    • Inspect the harness connectors and the ground circuits of the fuel pump for poor connections
    • If a condition exists 

      Repair as necessary.

    • Go to next step: If no conditions exist 

      Go to next step: Replace the G12 Fuel Pump.

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