Troubleshooting Ford Escort Fuel Cut-Off Problems

by Lee Sallings

The Ford Escort, like many Ford cars and light trucks, comes equipped with a fuel-pump shut off. This fuel-pump shut off, called an inertia switch, prevents fuel from being pumped to the engine in the event of an accident like a rear end collision or rollover. A defective inertia switch will cause the fuel pump to shut off and the engine to not start.

Circuit Function

This switch activates when a metal ball that is magnetically held against two contacts is knocked loose by the impact. Reset the switch by pushing the reset button located in the trunk or under the right side of the dash.

Power to the circuit is supplied to the switch by the fuel pump relay when the relay is energized by the on-board computer. The ground circuit is through the switch first, then through the fuel pump.

Testing the Switch

To test the switch and determine if it's a bad switch and not a bad fuel pump, push the reset button. These switches can be tripped by a sharp blow to the trunk lid---sometimes all that is needed is a reset

If the vehicle still fails to start, unplug the wiring connector at the switch and test for power on one side of the connector and ground on the other side. This is the normal state of the circuit. Power comes from the fuel-pump relay, and ground is found through the fuel pump. If there is no power, but there is ground, the fuel pump relay or fuel pump fuse could be the defective part. No ground indicates a wiring problem to the fuel pump or a defective fuel pump.

If you have power and ground, install a jumper wire to bypass the switch. If the engine will start and run normally, then the switch can be called defective. If the engine still does not start, check for power at the fuel pump. If there is power and ground at the fuel pump, then the fuel pump can be called defective.

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