disclosed is a fuel supplying device of an internal combustion engine , comprising a low - pressure circuit , a high - pressure pump coupled to the low - pressure circuit and conveys fuel into a fuel reservoir , a volume flow control valve assigned to the high - pressure pump , an electromechanical pressure regulator connected to the fuel reservoir and the low - pressure circuit and can direct fuel from the fuel reservoir into the low - pressure circuit , a regulating mechanism which generates an actuation signal for the volume flow control valve by a first controller in a first mode which generating an actuation signal for the electromechanical pressure regulator with the aid of a second controller in a second mode . the mode of the fuel supplying mechanism is switched in accordance with a fuel pressure error value resulting from a detected fuel pressure and a predefined fuel pressure . the mode can additionally be switched according to the throughput of the high - pressure pump .