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Home >> Pontiac >> 2009 >> Vibe Base, 2.4 0, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 157 (Engine Controls And Fuel - 4.6L - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Fuel System Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2011 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
    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, engine OFF, command the fuel pump relay ON with a scan tool and observe the fuel pressure gauge while the fuel pump is operating. Verify the fuel pressure is between 384-425 kPa (55-62 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. If all items test normal, replace the fuel pump module.
    • Restricted fuel feed pipe
    • Restricted or plugged strainer
    • 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 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 (CH 48027) , Fuel Pressure Relief (Without CH 48027) .
    2. Install the J 37287  Adapter between the fuel feed pipe and the fuel rail.
    3. Open the valve on the J 37287  Adapter
    4. Ignition ON, command the fuel pump relay ON with a scan tool and bleed the air from the CH 48027  Gauge.
    5. Command the fuel pump relay ON and then OFF with a scan tool.
    6. 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 primary fuel pump module.
  4. Remove the J 37287  Adapter and the CH 48027  Gauge. Refer to Fuel Pressure Gauge Installation and Removal
  5. Operate the vehicle within the conditions of the customer's concern while monitoring the fuel pressure with the CH 48027  Gauge. 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 pump module.
    • Restricted fuel feed pipe
    • Restricted or plugged strainer
    • Inspect the harness connectors and the ground circuits of the fuel pump for poor connections
  6. If the fuel system tests normal, refer to Symptoms - Engine Controls .
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