LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2018 >> Suburban 3500 HD LT >> Repair and Diagnosis >> External Pages >> Different car >> Section 9 (Engine Controls And Fuel - 5.3L (L83) Or 6.2L (L86) - DTC P0443 To DTC P3452 And Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> Fuel System Diagnosis >> Circuit/System Verification

Circuit/System Verification

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Chevrolet Suburban, and 2018 Cadillac Escalade ESV. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
  • Repair all fuel system related DTCs before performing this diagnostic.
  • Inspect the fuel system for damage or external leaks before proceeding.
  • Verify that adequate fuel is in the fuel tank before proceeding.
  • The Fuel Pump Enable may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
  • 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 percent.
  1. Ignition ON, engine OFF, command the Fuel Pump Enable ON several times with a scan tool.
  2. Verify the scan tool Fuel Pressure Sensor parameter is between 320 - 580 kPa (46 - 84 psi) with the fuel pump running.
    • If less than 320 kPa (46 psi) 

      Refer to Circuit/System Testing - Fuel Pressure Low.

    • If greater than 580 kPa (84 psi) 

      Replace the G12 Fuel Pump.

    • Go to next step: If between 320 - 580 kPa (46 - 84 psi) 
  3. Verify that the fuel pressure decreases to 468 - 544 kPa (68 - 79 psi) after the fuel pump is turned off.
    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.
    • If the fuel pressure does not decrease to 468 - 544 kPa (68 - 79 psi) 

      Replace the G12 Fuel Pump.

    • Go to next step: If the fuel pressure decreases to 468 - 544 kPa (68 - 79 psi) 
  4. Verify that the fuel pressure does not decrease greater than 34 kPa (5 psi) in 1 minute.
    • If the fuel pressure decreases greater than 34 kPa (5 psi) 

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

    • Go to next step: If the fuel pressure does not decrease greater than 34 kPa (5 psi) 
  5. Relieve the fuel pressure to 69 kPa (10 psi), refer to Fuel Pressure Relief .
  6. Verify that the fuel pressure does not decrease greater than 14 kPa (2 psi) in 5 minutes.
    • If the fuel pressure decreases greater than 14 kPa (2 psi) 

      Replace the G12 Fuel Pump.

    • Go to next step: If the fuel pressure does not decrease greater than 14 kPa (2 psi) 
  7. Operate the vehicle within the conditions of the customer's concern while monitoring the Fuel Pressure Sensor parameter with a scan tool.
    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.
  8. Verify the fuel pressure does not drop off during acceleration, cruise or hard cornering.
    • If the fuel pressure drops off 

      Refer to Circuit/System Testing - Fuel Pressure Drops OFF.

    • Go to next step: If the fuel pressure does not drop off 
  9. If the fuel system components test normal, refer to Symptoms - Engine Controls , Fuel Injector Diagnosis  and Fuel Injector Balance Test  for further diagnosis.
scientia non olet · About LEMON Manuals