Replacing a car's main engine control computer can be expensive, and at times a workaround is a good option if only one output circuit -- such as the one controlling the fuel pump -- is the only malfunctioning part of the computer control system. If all the other circuits are working properly (the ignition, the fuel injection and the emissions management systems), then hard-wiring the fuel pump is not only a viable, but also a safe and straightforward procedure.
Raise the hood of the car and locate the power center. Raise the lid of the power center; under the lid, find a diagram with a listing of all the relays and fuses. Locate the fuel pump relay and remove it -- on its side is a diagram of the relay connections. Refer to the connection numbers and find, in a service manual, a listing of each connection and where it goes. Of the four connections, one comes from the engine computer and supplies a ground signal to the relay. This causes the relay to close and send power to the fuel pump.
Locate, in the service manual, the color of the wire that supplies a negative signal to the relay from the computer. Remove the wire harness cover that goes to the power center; locate the color of the wire and use wire cutters to snip it in half. Strip the wire back and install a wire crimp with a new section of wire that goes from the power center to the dashboard.
Run the sectioned wire through the firewall to the driver's dashboard area. Locate an area under the dashboard and drill a 1/2-inch hole. Mount a toggle switch in the hole. Install the wire that runs from the power center to one of the prongs of the toggle switch.
Cut another small section of wire and install a wire crimp connector on both ends. Install one end on the empty prong of the toggle switch, and the other end to a clean area of metal under the dashboard to complete a negative circuit.
Test the circuit. Turn the key on, turn the toggle switch to the "On" position, and start the car.
