LEMON Manuals: Even more car manuals for everyone
Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 6 (Engine Controls And Fuel - 6.0L (L96) - Description And Operation) >> Description And Operation >> Fuel System Description >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. 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 below.

    • 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. 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.

  3. Verify that the fuel pressure decreases to 468 - 544 kPa (68 - 79 psi) after the fuel pump is turned off.
    • 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 below.

    • 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. 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.

  7. Operate the vehicle within the conditions of the customer's concern while monitoring the Fuel Pressure Sensor parameter with a scan tool.
  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 below.

    • 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