Fuel pump mainly by the pump, permanent magnet motor and the shell of three parts. The working principle is: After the permanent magnet motor drives the pump body to rotate, the fuel is sucked in from the oil sump, flows through the inside of the electric fuel pump, and then is pressed out from the oil outlet to supply oil to the fuel system. Electric fuel pump shell crimping riveting at both ends, so that the various components of a non-removable assembly, the electric fuel pump is generally not repaired. Additional features of the fuel pump by the safety valve and check valve to complete the role of safety valve is to avoid the fuel pipeline obstruction, the pressure is too high cause pipe rupture or damage the fuel pump phenomenon. The relief valve has a nominal pressure of 2.6 bar and the check valve is set to prevent oil from sealing the circuit when the fuel pump is out of service, keeping the fuel system at a residual pressure so that the engine can be easily started the next time. The electric fuel pump is installed on the bottom shell inside the fuel tank of the vehicle, and the bottom shell of the fuel tank is provided with a sump partially subsided. The oil pump sucks oil from the sump when it is working. The oil outlet is connected with the external oil supply pipe through the fuel tank cap through the oil pipe. The upper part of the pump cover by the fuel tank cap and gasket, the pump tightly pressed in the tank. There is oil on the pump, oil return gauge arrow, according to the arrow to determine the pipeline connection. Pump circuit connection: Pump circuit has 5 connections, of which 2 for the pump power supply, the other 3 way for the liquid level display. Power circuit red "+" pole, the pole should be connected to the EFI system harness connector, the power control by the relay ECU control. Fuel pump fuel flow rate of 80L / hour, the excess oil recirculation, into the fuel tank, the fuel in the process of flushing and cooling spray body. Electric fuel pump is good or bad judge: a. Before the electric fuel pump is damaged, its noise is obviously increased compared with the normal time, and it can be judged by listening to the sound. b. Detection of electric fuel pump armature winding resistance, the general resistance of 10 ~ 20Ω or so, if the resistance is too large or too small, indicating the electric fuel pump armature winding a short circuit, poor brush contact or bypass block Other failures. c. Check the electric fuel pump oil output: Remove the electric fuel pump out of the tubing, the electric fuel pump terminal through the 11.5V voltage, the amount of fuel collected from the fuel outlet, 30 seconds within the pump oil Should not be less than 0.6 liters, otherwise the pump is a safety valve failure. Electric fuel pump can not be repaired, when it is judged as damaged, it must be replaced. Electric fuel pump removal and installation, must be cut off the total power supply. Computer-controlled fuel pump features: When the fuel pump is connected, the ignition switch is connected to the second gear position, the oil pump starts, if within 10 seconds the ECU receives the engine speed signal is less than the minimum starting speed or engine shutdown, the pump power Was cut off, the purpose is to prevent the long-term work of the pump, and cut off the oil in case of unexpected situations. When the engine is running or starting conditions, the pump power is on.