Inertia Fuel Shutoff (IFS) Switch: Notes
WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2004 Mercury Sable, 2004 Mercury Mountaineer, 2004 Mercury Monterey, 2004 Mercury Marauder, and 2004 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.
The inertia fuel shutoff (IFS) switch (Fig 1) is used in conjunction with electric fuel close valves. The purpose of the IFS switch is to close the fuel shut-off valves if a crash occurs. It consists of a steel ball held in place by a magnet. When a sharp impact occurs, the ball breaks loose from the magnet, rolls up a conical ramp and strikes a target plate which opens the electrical contacts of the switch and closes the electric fuel shut-off valve. Once the switch is open, it must be manually reset before restarting the vehicle . On some vehicles a fuel reset light illuminates. Refer to the Owner Guide for the location of the IFS.