How to Change a Fuel Pump Relay

by Chris Moore

The fuel pump relay helps your vehicle start up the car by pressurizing the fuel system for the first few seconds before the oil pressure's level takes over. A bad fuel pump relay means the fuel system can't build enough pressure to send gas to the engine, so the car won't start. The relay must be replaced if this happens. The fuel pump relay is usually located in the vehicle's long black box with the other relays and fuses. The location can be different, however, in some other cars.

Disconnect the cable from the vehicle battery's negative terminal to shut off the power. Disconnecting the positive terminal is also a good precaution.

Open the hood and check inside the fuse box in the engine compartment. The fuel relay is located here on most cars. Check the underside of the fuse box lid for a diagram showing the fuses/relays in the box and their locations. If the relay is not in the fuse box, check the manual or with your mechanic.

Remove the fuel pump relay, which is a cube-shaped object that connects with prongs like an electrical plug. Disconnect the plug-in (and fuse, if needed) to the relay to remove it. If the relay is within the box, pry it out carefully with the help of a flathead screwdriver.

Use the old relay as a guide to get the correct replacement at an auto supply store. A new relay can range in price from $12 to $45. Some relay brands can be more reliable than others. Check with a store specialist for the best relay brand for your vehicle.

Install the new relay into place in the vehicle. Reconnect the plug-in, fuse and any other connectors. Reconnect the battery cables.

Repressurize the fuel system, as it should have depressurized after removing the relay. Make sure the gas cap is secure, then turn the ignition on for 2 seconds and shut it off for up to 10 seconds. Repeat at least 5 times; the recommended number can vary, depending on the vehicle.

Tip

  • check You can test the fuel pump relay by swapping it with a similar one in the fuse box. The air conditioner relay is often close enough. If the car starts with the second relay connected, the fuel pump relay is bad.

About the Author

Chris Moore has been contributing to eHow since 2007 and is a member of the DFW Writers' Workshop. He received a Bachelor of Arts in journalism from the University of Texas-Arlington.