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HOMESERVICE MANUALSGMC2009CANYON 4D PICKUP, 2.9 9REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 9 (ENGINE CONTROL SYSTEM & FUEL SYSTEM - 5.3L - TROUBLESHOOTING & DIAGNOSIS)FUEL SYSTEM DIAGNOSISCIRCUIT/SYSTEM TESTING
2009 GMC Canyon 4D Pickup, 2.9 9

Circuit/System Testing

2009 GMC Canyon 4D Pickup, 2.9 9SECTION Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
    NOTE:
    • 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 345-414 kPa (50-60 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
      • Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
    2. 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.
  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)Fuel Pressure Relief (Without CH-48027) .
      2. Install the J 37287:  Shut-Off Adapters between the fuel feed pipe and the fuel rail.
      3. Open the valve on the J 37287:  Shut-Off Adapters.
      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:  Shut-Off Adapters.
      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. Operate the vehicle within the Conditions of the customer's concern while monitoring the fuel pressure with the CH 48027:  Gage. 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 fuel sender.
      • 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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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.