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HOMESERVICE MANUALSCHEVROLET2009MALIBU LS, 3.5 NREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS AND FUEL - 3.5L - TROUBLESHOOTING & DIAGNOSISFUEL SYSTEM DIAGNOSISCIRCUIT/SYSTEM TESTING
2009 Chevrolet Malibu LS, 3.5 N

Circuit/System Testing

2009 Chevrolet Malibu LS, 3.5 NSECTION 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, engine OFF, 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 384-425 kPa (56-62 psi).
    • If the fuel pressure is greater than the specified range, replace the fuel pump module.
    • If the fuel pressure is less than the specified range, test, inspect, and repair the items listed below:
      • Restricted fuel feed pipe
      • Restricted or plugged strainer
      • The harness connectors and the ground circuits of the fuel pump for poor connections
    • If all items test normal, replace the fuel pump module.
  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 (With CH 48027-100) or Fuel Pressure Relief (Without CH 48027-100) .
      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 CH-48027  .
      5. Command the fuel pump relay ON and OFF with a scan tool.
      6. Close the valve on the J 37287  .
      7. Monitor the fuel pressure for 1 minute.
        • If the fuel pressure decreases more than 34 kPa (5 psi) within the specified time, locate and replace the leaking fuel injectors.
        • If the fuel pressure does not decrease more than 34 kPa (5 psi) within the specified time, replace the fuel pump 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 fuel pump module.
  4. Operate the vehicle within the conditions of the customers concern while monitoring the fuel pressure with the CH-48027  . 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:
      • Restricted fuel feed pipe
      • Restricted or plugged strainer
      • The harness connectors and the ground circuits of the fuel pump for poor connections
    • If all items test normal, replace the fuel pump module.
  5. If the fuel system tests normal, refer to Symptoms - Engine Controls .
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.