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Home >> Chevrolet >> 2007 >> Optra LS, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 1.8L (LDA) >> 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 and observe the fuel pressure gage while the fuel pump is operating. Verify the fuel pressure is between 380-427 kPa (55-62 psi).
    • If the fuel pressure is greater than the specified range, replace the fuel pump.
    • If the fuel pressure is less than the specified range, remove the fuel tank and test, inspect, and repair the items listed below. If all items test normal, replace the fuel pump.
      • Restricted fuel feed pipe
      • Restricted or plugged fuel filter
      • Restricted or plugged strainer
      • Stuck or binding fuel level float
      • Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
    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:
      1. Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief .
      2. Install the J 37287  between the fuel feed pipe and the fuel rail.
      3. Open the valve on the J 37287  .
      4. Ignition ON, command the fuel pump relay ON with a scan tool and bleed the air from the fuel pressure gage.
      5. Close the valve on the J 37287  .
      6. Verify that the fuel pressure does not decrease more than 34 kPa (5 psi) in 1 minute.
        • If the fuel pressure drops, locate and replace the leaking fuel injector.
      7. If the fuel system test normal, replace the fuel pump.
  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 fuel pressure gage.
  5. Operate the vehicle within the conditions of the customers concern while monitoring fuel related parameters with a scan tool. The scan tool parameters should not indicate a lean condition.
    • 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.
  6. If the fuel system components test normal, refer to Symptoms - Engine Controls .
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