To provide a fuel supply system of an internal combustion engine in which an electromagnetic valve or the like need not be provided, requests for both high power and low fuel consumption can be satisfied, and further a simple structure and high reliability can be realized.

The fuel supply system is equipped with pump controllers 59, 60 which control an operation of a fuel pump 21 so as to supply a required injection quantity of fuel to an injector 31; a low-pressure regulator 71 including a regulated pressure port 71a connected with a fuel pathway P1 at a supply side and a return port 71b communicating with a fuel reservoir chamber 11 at a pump side; a high-pressure regulator 72 including a regulated pressure port 72a connected with the fuel pathway P1 at the supply side, and a return port 72b communicating with a fuel reservoir room 11 at the pump side; transfer pumps 76, 77 which transfers fuel from other fuel reservoir chambers 12, 13 to the reservoir chamber 11 depending on a fuel flow returning from the port 71b to the reservoir room 11; and an orifice 81 which is located in a fuel pathway P2 at a return side and limits a fuel flow returning to the reservoir room 11 depending on an anteroposterior pressure difference.

COPYRIGHT: (C)2008,JPO&INPIT