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Home >> Chevrolet >> 2006 >> Optra LS, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 1.6L (L91) >> Diagnostic Information and Procedures >> Fuel System Diagnosis >> Circuit/System Testing
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Circuit/System Testing

    IMPORTANT:
    • The fuel pump relay 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, command the fuel pump relay ON with a scan tool. Verify the fuel pressure is between 262-303 kPa (38-44 psi).
    • If the fuel pressure is more then the specified range, replace the fuel pump.
    2. IMPORTANT: 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.
  2. Verify that the fuel pressure does not decrease more than 34 kPa (5 psi) in 1 minute.
    • If the fuel pressure decreases more than the specified value, perform the following procedure:
      • Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure .
      • Install the J 37287  between the fuel feed pipe and the fuel rail. See Special Tools .
      • Open the valve on the J 37287  . See Special Tools .
      • Bleed the air from the fuel pressure gage.
      • Close the valve on the J 37287  . See Special Tools .
      • Verify that the fuel pressure does not decrease more than 34 kPa (5 psi) in 1 minute.
        • If the fuel pressure remains constant, replace the fuel pump.
        • If the fuel pressure drops, locate and replace the leaking fuel injector.
  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 fuel pump.
  4. Remove the J 37287  and J 34730-1A  . See Special Tools . Refer to Fuel Pressure Gage Installation and Removal .
  5. Operate the vehicle within the conditions of the customer concern while monitoring fuel related parameters with a scan tool.
    • If the scan tool parameters indicate a lean condition, test for a restricted fuel feed pipe, restricted fuel filter, or poor connections at the harness connectors and ground circuits of the fuel pump. If all test normal, replace the fuel pump.
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