What Is a Fuel Pump Relay Switch?

by Alicia Crowder

The fuel pump relay switch gets the fuel pump running in the vehicle during the start cycle. The terms fuel pump relay and fuel pump relay switch are used interchangeably. The fuel pump relay begins its job when the automobile operator turns to the ignition on, but before the motor is actually running. At that point, the fuel pump relay in some cars sends a signal to the ignition switch, which in turn sends a signal to the fuel pump to turn on. Others fuel pump relays have actual circuitry inside of them that receive the ignition signal and directly signal the fuel pump to engage.


Fuel Pump Relay Switch

The fuel pump is always turned off by default. The fuel pump gets the fuel out of the gas tank and by force transfers it into the fuel injection system. The fuel injection system is what modern cars have instead of the carburetor. The fuel pump relay switch is what gets the fuel pump to turn on in order to begin this process. Without the fuel pump relay switch the entire process of fueling the engine cannot usually begin.



The fuel pump relay switch is located in different places in different types of vehicles. Some are located under the dashboard near the steering column. Others are located on the firewall. The firewall is the wall located at the back of the engine area. Many are located right by the fuel pump, which is often right inside the fuel tank. The fuel pump relay switch is often put in your car after the engine is put together and in whatever location the manufacturer of the vehicle finds to be the most convenient placement. The first place you should check is under the hood in the fuse box.

Identify a Fuel Pump Relay Switch Problem

A fuel pump relay switch should never be hot to the touch. If your fuel pump relay is hot, you probably need to replace it. When your car is having trouble that is connected to the fuel pump relay it is possible that the contacts on your relay are bad. You can have these tested at an auto store. If your car is not starting or if there is a burnt smell, you may also want to check your fuel pump relay switch, as these are two common indicators that you are having a problem with the relay.

How to Test

The air conditioning of your automobile may use a similar relay as your fuel pump relay switch. You may be able to take the air conditioning relay out and replace it with the fuel pump relay in order to test it and see if it is working.


Fuel pump relay switches can be purchased for anywhere from $20.00 to $200.00 depending on the make, year and model of your vehicle. Any auto parts store will either carry these or can order them and have them in store for you within a few days.

About the Author

Alicia Crowder is a full-time freelance writer. Her portfolio includes work for Free Press Houston, Nevermore magazine, Public News and online content. She has published one non-fiction book and written book reviews for multiple sites. Crowder also has experience as a technical writer of construction project specifications and computer software user manuals.

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