What happens when you have a bad Fuel Pump Inertia Switch?

A fuel pump inertia switch is designed to shut off the fuel pump when your vehicle is involved in an accident so fuel doesn't keep pumping creating a fire hazard. If it fails in such a way that it cuts off your fuel pump constantly your vehicle will not start. If it fails in such a way that the inertia sensor doesn't work you are at a higher risk of having a fire in your vehicle in involved in an accident.