A fuel pressure regulation system for a compression ignition diesel engine. The system comprises a fuel supply line connected to an inlet of a transfer pump and a transfer pressure fuel line connected between the transfer pump outlet and the high pressure fuel pump inlet. A fuel filter is positioned in the transfer pressure fuel line and a fuel spill line fluidly connects a fuel pressure regulator to the transfer pressure fuel line at a point between the transfer pump outlet and the fuel filter. A fuel return line is connected between the fuel pressure regulator and the fuel supply line and a control fuel line is connected between the fuel pressure regulator and the transfer pressure fuel line. The fuel pressure regulator comprises a bore within which is located a valve member moveable from a non-regulating position of the fuel pressure regulator to a regulating position of the fuel pressure regulator. In use, any fuel entering the bore through a control fuel line connection acts upon a valve member thrust surface which results in a force acting to open the fuel pressure regulator. Any fuel entering the bore through the fuel spill line connection enters a region between the first end and the second end of the bore. There is provided a leak passageway connected from a point between the first and second ends and a fuel return line connection. In normal operating use, a fuel flow path from the fuel spill line connection to the fuel return line connection is kept open when the fuel pressure regulator is in the non-regulating position.