An improved fuel pressure regulation system and an improved fuel pressure regulator for use therein

A fuel pressure regulator (1,201) for a compression ignition diesel engine. The regulator (1, 201) comprises a bore (5,205) within which is located a valve member (3,203) that is moveable from a non-regulating position to a regulating position. In a non-regulating position a first end (11,211) of the bore (5,205) is closed. In a regulating position the first end of the bore (5,205) is open. A control fuel line connection (8,208) is positioned at a second end (9,209) of the bore (5,205), such that, in use, any fuel entering the bore (5,205) through the control fuel line connection (8,208) acts upon a thrust surface (12,212) provided on the valve member (3,203) resulting in a force acting on the valve member (3,203) in a direction to open the fuel pressure regulator (1,201). There is provided an upper clearance (6,206) between the valve member (3,203) and the second end (9,209) of the bore (5,205), and a fuel spill line connection (13,213) positioned in the bore (5,205) such that, in use, any fuel entering the bore (5,205) through the fuel spill line connection (13,213) enters a region between the first end (11,211) and the second end (9,209) of the bore (5,205). A lower clearance(30,230) is provided in the bore (5,205) between the first end (11,211) and the second end (9,209), and a leak passageway is connected from a point between the lower clearance(30,230) and the second end (9,209) of the bore (5,205), and a fuel return line connection (14,214), such that, in normal operating use, a fuel flow path from the fuel spill line connection (13,213) to the fuel return line connection (14,214) is kept open when the fuel pressure regulator (1,201) is in the non-regulating position.