How to diagnose the fuel pump?
The first thing you need to check the fuse, which protects the device. If it’s not there, you will need to inspect the fuel line for leaks. Much attention should be paid to the point of connection of hoses and pipes. Thereafter, the fuel pump relay is checked, as well as electrical contacts. These contacts can be oxidized, so the solution can be easy to clean. The next step is to check the voltage at the terminals of the fuel pump. With the engine off, it should be in the range of 12 volts.
If all of the above would be normal, the next step is to measure the pressure in the fuel system. Before measurements, relieve residual pressure in the fuel system. For this purpose, the device is disconnected from the socket, or the fuse and the fuel pump relay are removed. After that, start the engine and wait until the pressure drops to zero and it will stall. When this happens, the measurements will be possible.
Most often fitting is in the fuel rail. A pressure gauge is connected to it. If there is no connection at the fuel rail, the measurement device is connected through the tee directly to the fuel. After that, turn on ignition. The pump pumps up fuel for about two seconds.
During this time, the device must be in good time to raise the pressure in the injection system to the required level. Specific figures should be reflected in the repair manual and operation of the vehicle.