The powertrain control module (PCM) determines the speed of the fuel pump based on the engine speed signal and the basic injection quantity information of the fuel injector. The speed of the fuel pump is transmitted by duty signal from the PCM to the fuel pump control module. Based on this duty signal, the fuel pump control module controls the drive voltage of the fuel pump. In this way, fuel is supplied in a flow volume corresponding to the engine requirements. The fuel pump control module has a failure detection function and a fail-safe function, and in case of a system malfunction, a failure detection signal is sent to the PCM, causing the fuel pump to be locked in the high mode. This prevents engine damage from insufficient fuel supply.