The inertia switch is a safety item incorporated by Ford in the fuel system of its vehicles. The only time the inertia switch should trip is during a collision. However, there are other occurrences that can trip an inertia switch, such as a blown tire or simply hitting a pothole in the road. If you have a Ford fuel pump that is not operating properly, always be sure to check your inertia switch.
On the top of the inertia switch is a red button. With the inertia switch in the open position, the red button is raised up. It is not supplying power to the fuel pump in this position. When the reset button is pushed in (or down), then the inertia switch will let the voltage flow to the fuel pump.