Inertia Fuel Shutoff Switch: Description and Operation

Typical Inertia Fuel Shut-Off Switch:

CONSTRUCTION
The Inertia Fuel Shutoff Switch (IFS) consists of a steel ball held in place by a magnet.

PURPOSE
The IFS switch is used in conjunction with an electric fuel pump and shuts off the fuel pump in the event of a collision.

When a sharp impact occurs, the ball breaks loose from the magnet, rolls up a ramp and strikes a target plate which opens the electrical contacts of the inertia fuel shutoff switch and shuts off the fuel pump.

The fuel pump module will shut off even if the engine continues to run. However, the engine will stall a few seconds after the fuel pump module shuts off