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Fuel System Pressure Release

CAUTION: Do not allow smoking or the use of open flames in the area where work on the fuel or EVAP system is taking place. Anytime work is being done on the fuel system, disconnect the negative battery cable, except for those tests where battery voltage is required.
NOTE: Gauge Bar Set (SA9127E) is required to perform this procedure if scan tool is not being used to relieve fuel pressure. See Figure .

Fuel pressure may be relieved by using one of following methods:

  1. Start and run vehicle then disable the fuel pump using a scan tool. This method is the cleanest since no fuel, under pressure, will be present at any fitting or connection that needs to be serviced. This method is preferred when removing any components of the fuel system that require disconnecting fuel lines. If performance tests are to be run on the system underhood, step No. 2 will be preferable since the Gauge Bar Set will also be required for testing. This method is also preferable to disconnecting the fuel pump relay since no DTCs will be set and there is no concern about voltage spikes to the ECM if the relay should be installed with the key ON.
    • Connect the scan tool and start the vehicle.
    • Turn the scan tool ON and locate SPECIAL FUNCTIONS.
    • Select POWERTRAIN.
    • Select FUEL SYSTEM.
    • Select FUEL PUMP.
    • Command the fuel pump OFF.
    • The engine will die in 3-5 seconds.
  2. Bleed pressure at the service test port. This method will require collection of fuel as pressure is relieved. Use of a suitable container is required.
    • Locate the service test port on the fuel rail and remove the protective cap.
    • Connect the Gauge Bar Set using the Fuel Gauge Pressure Adapter (309725) and flexible hose from the Gauge Bar Set.
    • Make sure the needle valve on the Fuel Gauge Pressure Adapter is closed (OFF).
    • Connect the Fuel Gauge Pressure Adapter to fuel line test port. Do not use any tools to tighten the adapter to the fuel line pressure port. If the adapter will not seal with finger tightening, then the seal is defective or damaged and needs to be replaced. Excessive torque on the adapter will damage the fuel line test port.
    • Connect the Fuel Gauge Pressure Adapter to fuel line test port.
    • Route the drain hose from the Fuel Gauge Pressure Adapter into a suitable container or route the fuel back to the fuel tank.
    • Open the valve on the Fuel Gauge Pressure Adapter and bleed off the pressure and fuel.

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