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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1978 (Engine Controls And Fuel - 3.5L - Troubleshooting & Diagnosis) >> Fuel System Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT:
    • The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
    • DO NOT start the engine.
  1. Ignition ON, engine OFF, command the fuel pump ON with a scan tool and observe the fuel pressure gage while the fuel pump is operating. Verify the fuel pressure is between 384-425 kPa (56-62 psi).
    • If the fuel pressure is greater than the specified range, replace the primary fuel tank module.
    • If the fuel pressure is less than the specified range, test, inspect, and repair the items listed below. If all items test normal, replace the primary fuel tank module.
      • Restricted fuel feed pipe
      • Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
  2. Verify that the fuel pressure does not decrease more than 100 kPa (14.5 psi) in 5 minutes.
    • If the fuel pressure decreases more than the specified value, perform the following procedure:
      1. Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief (With CH 48027-100) or Fuel Pressure Relief (Without CH 48027-100) .
      2. Disconnect the chassis fuel feed hose from the engine compartment fuel pipe. Refer to Metal Collar Quick Connect Fitting Service .
      3. Connect the chassis fuel feed hose to the inlet side of SA9127E-7  using the J 43937  .
      4. Connect the engine compartment fuel pipe to the ON/OFF valve side of the SA9127E-7  using the J 43937  .
      5. Cap the pressure test port on the SA9127E-7  with the J 43936  .
      6. Open the valve on the SA9127E-7  .
      7. Ignition ON, command the fuel pump ON with a scan tool and bleed the air from the CH-48027-100  .
      8. Command the fuel pump ON for a minimum of 10 seconds with a scan tool.
      9. Close the valve on the SA9127E-7  .
      10. Monitor the fuel pressure for 5 minutes.
        • If the fuel pressure decreases more than 55 kPa (8 psi) within the specified time, locate and replace the leaking fuel injectors.
        • If the fuel pressure does not decrease more than 55 kPa (8 psi) within the specified time, replace the primary fuel tank module.
  3. Relieve the fuel pressure to 69 kPa (10 psi). Verify that the fuel pressure does not decrease more than 14 kPa (2 psi) in 5 minutes.
    • If the fuel pressure decreases more than the specified value, replace the primary fuel tank module.
  4. Operate the vehicle within the conditions of the customer's concern while monitoring the fuel pressure with the CH-48027-100  . The fuel pressure should not drop off during acceleration, cruise, or hard cornering.
    • If the fuel pressure drops off, test, inspect, and repair the items listed below. If all items test normal, replace the primary fuel tank module.
      • Restricted fuel feed pipe
      • Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
  5. If the fuel system tests normal, refer to Symptoms - Engine Controls .
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