PURPOSE: To prevent the deterioration of HC and particulate by providing a secondary fuel return line branched from a fuel return line up an electromagnetic valve and connected to a low pressure pump chamber, providing a valve mechanism in that line, and opening it in high speed and no load conditions.

CONSTITUTION: When an accelerator pedal is released in running at high speed, it is judged to be in high speed and no load conditions, an electromagnetic valve 25 (valve mechanism) provided in the second fuel return line 21 is opened to connect a fuel return line 13 to a line 23, and a plunger chamber is connected to a low pressure pump chamber 5 through the line 21. By this, even when a plunger pump operation enters compression stroke, fuel from the plunger chamber is quickly forced back to the pump chamber 5 through the line 21, and fuel cut is made without increasing the fuel pressure in the plunger chamber.