A fuel pump having a pump housing with a first lifter bore, a fuel inlet aperture, a fuel bypass aperture, and a crankcase chamber is provided. The pump includes a first roller lifter coupled to a first pumping plunger. The pump includes a camshaft having a drive cam disposed in the crankcase chamber. The camshaft rotates the drive cam to reciprocate the first roller lifter within the first lifter bore. The fuel inlet aperture extends through the pump housing to the crankcase chamber. A fuel bypass aperture communicates with the fuel inlet aperture. The fuel inlet aperture routes fuel to the fuel bypass aperture which has not traversed through the crankcase chamber after entering the fuel inlet aperture. The fuel bypass aperture supplies the fuel to a valve. The pump includes a first anti-rotation pin that prevents rotation of the first roller lifter.
1 . A fuel pump, comprising:
a pump housing having a first lifter bore, a fuel inlet aperture, a fuel bypass aperture, and a crankcase chamber, the first lifter bore communicating with the crankcase chamber;
a first roller lifter being disposed in the first lifter bore; the first roller lifter being operably coupled to a first pumping plunger;
a camshaft having a drive cam disposed in the crankcase chamber, the drive cam contacting the first roller lifter, the camshaft being rotatable by an exterior motive force so as to rotate the drive cam to thereby reciprocate the first roller lifter within the first lifter bore;
the fuel inlet aperture extending through a portion of the pump housing to the crankcase chamber and being adapted to receive fuel therethrough;
the fuel bypass aperture communicating with the fuel inlet aperture above the crankcase chamber;
the fuel inlet aperture supplying a first portion of the fuel which has not traversed through the crankcase chamber after entering the fuel inlet aperture to the fuel bypass aperture, the fuel bypass aperture routing the first portion of the fuel to a fuel volume control valve, the fuel volume control valve supplying a portion of the first portion of the fuel to the first pumping plunger;
the pump housing having a first pin aperture extending through the pump housing to the first lifter bore; and
a first anti-rotation pin extending through the first pin aperture and into an elongated aperture of the first roller lifter to prevent rotation of the first roller lifter.
2 . The fuel pump of claim 1 , wherein:
the pump housing further having a second lifter bore, the second lifter bore communicating with the crankcase chamber;
a second roller lifter being disposed in the second lifter bore; the second roller lifter being operably coupled to a second pumping plunger;
the camshaft being rotatable by the exterior motive force so as to rotate the drive cam to thereby reciprocate the second roller lifter within the second lifter bore;
the fuel volume control valve supplying another portion of the first portion of the fuel to the second pumping plunger;
the pump housing having a second pin aperture extending through the pump housing to the second lifter bore; and
a second anti-rotation pin extending through the second pin aperture and into an elongated aperture of the second roller lifter to prevent rotation of the second roller lifter.
3 . The fuel pump of claim 2 , wherein:
the pump housing further having a control valve chamber and first and second fuel feed apertures; the fuel volume control valve being disposed in the control valve chamber;
the fuel bypass aperture communicating with and extending between the fuel inlet aperture and the control valve chamber; and
the fuel volume control valve communicating with the first and second fuel feed apertures.
4 . The fuel pump of claim 3 , wherein:
the fuel volume control valve receiving the first portion of the fuel from the fuel bypass aperture and metering the portion of the first portion of the fuel through the first fuel feed aperture to the first pumping plunger which pumps the portion of the first portion of the fuel from a first cylinder head, the fuel volume control valve metering the another portion of the first portion of the fuel through the second fuel feed aperture to the second pumping plunger which pumps the another portion of the first portion of the fuel from a second cylinder head.
5 . The fuel pump of claim 4 , further comprising:
a first spring retainer and a first spring;
the first pumping plunger being disposed in the first lifter bore and contacting the first roller lifter, the first pumping plunger extending through an aperture in the first spring retainer such that the first spring retainer is disposed in the first roller lifter;
the first spring being disposed around the first pumping plunger and contacting the first spring retainer;
the first cylinder head having a first central body, a first barrel portion, a first outlet port, a first upper tubular portion, and a first one-way check valve; the first one-way check valve being disposed in the first upper tubular portion and communicating with the first fuel feed aperture, a first longitudinal aperture extending through the first barrel portion and a portion of the first central body, the first outlet port having a first outlet aperture communicating with the first longitudinal aperture;
the first spring being further disposed around the first barrel portion and contacting the first cylinder head; and
the first pumping plunger being received in the first longitudinal aperture.
6 . The fuel pump of claim 5 , wherein:
when the first one-way check valve receives the portion of the first portion of fuel from the first fuel feed aperture and the first pumping plunger is moving downwardly toward the crankcase chamber, the first one-way check valve supplies the portion of the first portion of fuel to the first outlet aperture; and
when the first pumping plunger is moving upwardly away from the crankcase chamber, the first pumping plunger pumps the portion of the first portion of fuel through the first outlet aperture of the first outlet port.
7 . The fuel pump of claim 6 , further comprising:
a second spring retainer and a second spring;
the second roller lifter being disposed in the second lifter bore and operably contacting the drive cam;
the second pumping plunger being disposed in the second lifter bore and contacting the second roller lifter, the second pumping plunger extending through an aperture in the second spring retainer such that the second spring retainer is disposed in the second roller lifter;
the second spring being disposed around the second pumping plunger and contacting the second spring retainer;
the second cylinder head having a second central body, a second barrel portion, a second outlet port, a second upper tubular portion, and a second one-way check valve; the second one-way check valve being disposed in the second upper tubular portion and communicating with the second fuel feed aperture, a second longitudinal aperture extending through the second barrel portion and a portion of the second central body, the second outlet port having a second outlet aperture communicating with the second longitudinal aperture;
the second spring being further disposed around the second barrel portion and contacting the second cylinder head; and
the second pumping plunger being received into the second longitudinal aperture.
8 . The fuel pump of claim 7 , wherein:
when the second one-way check valve receives the another portion of the first portion of fuel from the second fuel feed aperture and the second pumping plunger is moving downwardly toward the crankcase chamber, the second one-way check valve supplies the another portion of the first portion of fuel to the second outlet aperture; and
when the second pumping plunger is moving upwardly away from the crankcase chamber, the second pumping plunger pumps the another portion of the first portion of fuel through the second outlet aperture of the second outlet port.
9 . The fuel pump of claim 1 , wherein:
the fuel inlet aperture routing a second portion of the fuel to the crankcase chamber for lubricating the drive cam;
a fuel outlet aperture extending into the pump housing; and
an overflow valve fluidly communicating with the crankcase chamber and the fuel outlet aperture such that the overflow valve supplies the second portion of the fuel from the crankcase chamber to the fuel outlet aperture when a pressure level in the crankcase chamber is greater than a threshold pressure level.