How to Replace the Fuel Injectors in Your Vehicle Part1 Removing the Old Injectors 1.Let your car cool down and disconnect the battery. The fuel injectors fire fuel into your engine’s cylinders, so you may start a fire if you remove them while your vehicle is running. Let the car cool off for 30-45 minutes if you were driving recently. Pop your hood and put some gloves on. Then, remove the battery terminals to disconnect the battery. .
