Patent ID: 8061328

Claim:
A fuel system comprising: a source of fuel; a source of lubrication fluid; a low pressure pump including: a low pressure pump inlet fluidly communicating with the source of fuel to define a fuel source flow path between the low pressure pump inlet and the source of fuel; and a low pressure pump outlet; a high pressure pump including: a high pressure pump housing; a high pressure pump inlet formed in the high pressure pump housing and fluidly communicating with the low pressure pump outlet; a high pressure pump outlet formed in the high pressure pump housing; an internal bore formed in the high pressure pump housing and defining a pumping chamber fluidly communicating with the high pressure pump inlet and the high pressure pump outlet; a piston having a first end disposed in the internal bore and an opposite second end; a weep annulus formed in the high pressure pump housing and opening toward the internal bore; a seal disposed between the internal bore and the piston, the seal being located between the weep annulus and the piston second end; a cam operatively coupled to the piston second end; a cam housing enclosing the cam; a lubrication inlet fluidly communicating between the source of lubrication fluid and the cam housing; and a lubrication fluid outlet fluidly communicating between the cam housing and the source of lubrication fluid; a drain line fluidly connecting the weep annulus to the fuel source flow path and defining a fuel drain flow path; a T-connection coupled to the low pressure pump inlet, the T-connection defining a portion of the fuel source flow path and a portion of the fuel drain flow path so that the fuel drain flow path intersects the fuel source flow path at a substantially perpendicular angle; a common rail fluidly connected to the high pressure pump outlet; a plurality of fuel injectors fluidly connected to the common rail via individual branch passages; and an electronic controller in control communication with each of the plurality of fuel injectors and the high pressure pump, and wherein the electronic controller communicating a fuel injection timing and quantity control signal to each of the plurality of fuel injectors and a pump output control signal to the high pressure pump.