Inertia Fuel Shutoff Switch: Description and Operation

Fig. 17 Inertia switch:

This switch, Fig. 17, is used on all vehicles with electric fuel pumps. This switch shuts off the fuel pump in the event of an accident. The switch consists of a steel ball held in place by a magnet. Upon sharp impact, the ball breaks loose from the magnet, rolls up a conical ramp, and strikes a target plate that opens the switch electrical contacts and shuts off the fuel pump. Once the switch is open, it must be manually reset before starting the vehicle.