A fuel injection pump includes a cam rotating with a camshaft, a tappet reciprocating in response to rotation of the cam, a cylinder, a plunger, and a thrust washer. The thrust washer is located between the cam and a casing housing the camshaft at both ends of the cam in an axial direction of the cam. The tappet includes a tappet body, a roller, a supporting member, and a contact surface formed at an outer peripheral part of the tappet. The thrust washer includes a rotation restricting part that protrudes toward the tappet over a maximum lift position. The rotation restricting part restricts rotation of the tappet relative to a center axis of the tappet body by being contact with the contact surface.

A method of improving fuel delivery in an engine having one or more cylinders that are over-fueled related to other cylinders, such as a D-EGR engine. The fueling system uses a mechanical fuel pump, which is cam-driven. The cam has lobes corresponding to the desired displacement for each cylinder. The lobe corresponding to the over-fueled cylinder is shaped differently, such that the filling stroke of the pump is increased.

A fuel injection pump includes a cam rotating with a camshaft, a tappet reciprocating in response to rotation of the cam, a cylinder, a plunger, and a thrust washer. The thrust washer is located between the cam and a casing housing the camshaft at both ends of the cam in an axial direction of the cam. The tappet includes a tappet body, a roller, a supporting member, and a contact surface formed at an outer peripheral part of the tappet. The thrust washer includes a rotation restricting part that protrudes toward the tappet over a maximum lift position. The rotation restricting part restricts rotation of the tappet relative to a center axis of the tappet body by being contact with the contact surface.

A method of improving fuel delivery in an engine having one or more cylinders that are over-fueled related to other cylinders, such as a D-EGR engine. The fueling system uses a mechanical fuel pump, which is cam-driven. The cam has lobes corresponding to the desired displacement for each cylinder. The lobe corresponding to the over-fueled cylinder is shaped differently, such that the filling stroke of the pump is increased.