Patent ID: 8495987

Claim:
In a cam-driven high pressure single piston fuel pump having a body, a pumping chamber within the body, a piston with one end in the pumping chamber and another end outside the body, a piston sleeve secured to the body and having a bore in which the piston reciprocates between a retracting motion during which fuel is delivered to the pumping chamber and a pumping motion during which the piston pressurizes fuel in the pumping chamber, a non-hydraulic tappet bearing directly on the cam and directly on the other end of the piston to impart said pumping motion, and a piston return spring biasing the piston toward the tappet, wherein the improvement comprises that the piston return spring seats at the piston and a distinct tappet return spring seats at the tappet such that the tappet spring imparts no load on the piston.