The fuel pump is an important part of the electronic gasoline injection system of a car engine. Its basic function is to provide fuel with a certain pressure to the engine fuel injection system. Therefore, from this point of view, we can find that the quality of the electric fuel pump and the working condition will directly affect the working condition of the vehicle's fuel injection system. At the same time, it also greatly affects the fuel injection quality, vehicle power and fuel economy performance, and has a huge impact on the performance of the entire vehicle. 

The role of the fuel pump:
1. The function of the fuel pump is to extract the fuel from the fuel tank, filter it by the fuel filter, and send it to the pressure regulator, and then send it to the engine fuel distribution pipe and maintain a certain pressure. The fuel pump is divided into a built-in type that is immersed in the gasoline in the gasoline tank and an external type that is arranged outside the gasoline tank. Generally, the built-in type is adopted;
2. The roller oil pump itself has a cylindrical chamber with a disc-shaped rotor eccentrically arranged inside. There is a slot on the periphery of the rotor, and the roller is supported in the slot. The centrifugal force generated by the rotation of the rotor presses the rollers outwards, which acts as a peripheral seal;
3. The cavity enclosed by the rotor, rollers and pump body will change in volume with the rotation of the rotor. The fuel will be sucked on the side where the volume changes from small to large, and the fuel will be pushed out on the side where the volume changes from large to small;
4. When the ignition switch is turned on but the engine is not started, the fuel pump works for 2s to establish the oil pressure for starting. When the engine starts, the fuel pump is on. The electronic control unit ECU controls the operation of the fuel pump via an external fuel pump relay.