LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Controls And Fuel - 2.5L (LCV) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Fuel System Diagnosis >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
NOTE:
  • Verify the fuel tank is not empty before proceeding.
  • Do NOT perform the Fuel System Diagnosis if the engine coolant temperature is above 60°C (150°F). High fuel pressure readings may result due to hot soak fuel boiling. With the engine Off, the fuel pressure may increase beyond the pressure relief regulator valve's setting point of 690 kPa (100 PSI) ± 5%.
  1. Ignition - On / Vehicle - In Service Mode
  2. Verify there are no DTCs set related to the following component/system: Fuel System
    • Go to next step: If a related DTC is not set 
  3. Verify the following conditions do not exist:
    • Hoses / Lines @ Fuel System - Kinked/Leaking/Restricted/Visible Damage
    • Components @ Fuel System - Leaking / Visible Damage - Refer to: Fuel Leak Diagnosis 
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  4. Perform the following procedure/test: Fuel Pressure Relief

    Verify the scan tool parameter: Fuel Pressure Sensor = Less than 83 kPa (12 PSI)

    • If 83 kPa (12 PSI) or greater 

      Replace the component: B47 Fuel Pressure Sensor

    • Go to next step: If less than 83 kPa (12 PSI) 
    5. NOTE:

    The fuel pump may need to be commanded On a few times in order to obtain the highest possible fuel pressure.

  5. Perform the scan tool control function: Fuel Pump Enable - On - Command the function On several times.

    Verify the scan tool parameter: Fuel Pressure Sensor = 320 to 608 kPa (46 to 88 PSI)

    • If less than 320 kPa (46 PSI) 

      Refer to: Circuit/System Testing - Fuel Pressure Low

    • If greater than 608 kPa (88 PSI) 

      Refer to: Circuit/System Testing - Fuel Pressure High

    • Go to next step: If between 320 and 680 kPa (46 and 88 PSI) 
    6. NOTE:

    The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.

  6. Verify the scan tool parameter: Fuel Pressure Sensor = Decreases between 468 and 544 kPa (68 and 79 PSI) - After the pump turns off.
    • If the parameter does not decrease between 468 and 544 kPa (68 and 79 PSI) 

      Replace the component: G12 Fuel Pump

    • Go to next step: If the parameter decreases between 468 and 544 kPa (68 and 79 PSI) 
  7. Verify the scan tool parameter: Fuel Pressure Sensor = Pressure drops less than 34 kPa (5 PSI) within 1 min.
    • If the pressure drops 34 kPa (5 PSI) or greater 

      Refer to: Circuit/System Testing - Fuel Pressure Leaks Down

    • Go to next step: If the pressure drops less than 34 kPa (5 PSI) 
  8. Relieve the pressure to 69 kPa (10 PSI).
  9. Verify the scan tool parameter: Fuel Pressure Sensor = Pressure drops less than 14 kPa (2 PSI) within 5 min.
    • If the pressure drops 14 kPa (2 PSI) or greater 

      Refer to: Circuit/System Testing - Fuel Pressure Leaks Down

    • Go to next step: If the pressure drops less than 14 kPa (2 PSI) 
    10. WARNING:

    Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

  10. Operate the vehicle within the conditions of the customer's concern while monitoring the scan tool parameter or tool: Fuel Pressure Sensor

    Verify the scan tool parameter: Fuel Pressure Sensor = The pressure should not drop off during acceleration, cruise or hard cornering.

    • If the pressure drops off 

      Refer to: Circuit/System Testing - Fuel Pressure Drops Off

    • Go to next step: If the pressure does not drop off 
  11. Perform the following procedure/test: Fuel Injector Diagnosis 

    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 
  12. Refer to: Symptoms - Engine Controls 
scientia non olet · About LEMON Manuals