DeVille, Eldorado, Seville 1999-2005

Relieving Fuel System Pressure


The fuel injection system remains under pressure, even when the engine has been turned OFF. The fuel system pressure must be relieved before disconnecting any fuel lines. Failure to do so may result in fire and/or personal injury.

  1. Before servicing vehicle, refer to the precautions at the beginning of this section.
  3. Loosen the fuel filler cap to relieve tank vapor pressure.
    Observe all applicable safety precautions when working around fuel. Whenever servicing the fuel system, always work in a well-ventilated area. Do not allow fuel spray or vapors to come in contact with a spark or open flame. Keep a dry chemical fire extinguisher near the work area. Always keep fuel in a container specifically designed for fuel storage; also, always properly seal fuel containers to avoid the possibility of fire or explosion.

  5. Be sure the ignition switch is in the OFF position.
  7. Disconnect the negative battery cable.
  9. Remove the engine cover.
    There may still be residual fuel in the system, and a small amount of fuel may be released when servicing fuel lines or connections. In order to reduce the chance of personal injury, cover the fuel line fittings with a shop towel before disconnecting to catch any fuel that may leak out.

  11. Install a fuel pressure gauge with a drain hose attached, J-34730- 1, or equivalent. Wrap a shop towel around the fitting while connecting the gauge to avoid spillage.

    Click image to see an enlarged view

    Fig. View of the fuel rail assembly, showing the fuel system service port location

  13. Install the drain hose into an approved container and open the valve to drain the system pressure. Fuel connections are now safe for servicing.
  15. Drain any remaining fuel from inside the gauge into the approved container.