Catch the Importance of fuel pump relay which is an electromagnetic switch that controls the power supply to the fuel pump. It is small but dramatically affects how well your car runs.   If you know what it does, how to test it, and how to repair it, you can save time, money, and possibly a lot of trouble. Before you start your car, remember the silent hero working behind the scenes: your trusty fuel pump relay. It keeps your car’s heart beating strong.