The fuel pump relay basically acts as an ON/OFF voltage control switch, allowing an electric current to flow to the pump/fuel injectors that supply fuel to the into the cylinders of the engine.
The fuel pump relay will be housed in the relay box, usually found underneath the dashboard. The relay connects to the car's battery, as well as connecting to the specific part that the relay is functioning, in this case the fuel injection pump.
In a diesel engine fuel injection is essential but petrol engines also have fuel injection systems. In a fuel injected engine, the electric fuel pump/fuel injector injection pump operates with a fuel pump relay, and works by spraying a light, high pressured mist of fuel from injectors into the chambers of the engine, controlled by the computerised control unit, which manages the timing of this process. The fuel pump relay opens and closes the contacts that provide voltage to the fuel pump/fuel injectors. The injectors are fitted close to the inlet manifold, one for each cylinder, and are all calibrated (adjusted) to equally spray a mist of fuel into the intake of each cylinder in a sequence controlled electronically, for the sequential firing of the engine. The overall result of this ensures the engine is working to its optimum, providing more power and fuel efficiency.
When you need to change the fuel pump relay, a good quality fuel pump relay will guarantee a part that fits well, performs properly and has a long service life. Relays can fail because of oxidisation, overheating or due to a faulty connection in the relay socket. Faults can occur with the electrical contacts, relay coil and wiring. The connections can overheat and corrode. If there is a problem with any of the relays in your car, the warning light should illuminate on the dashboard. It is always a good idea to consult with your mechanic when fuel system problems strike, to make sure the correct fault has been identified. It is important when replacing the fuel pump relay to buy a part that will be compatible with the make and model of your vehicle. Buying the fuel pump relay will guarantee you get the right component that's designed specifically for the make and model of your car.