3 during the intake stroke is less than during the pumping stroke then the tendency to cavitation upon aspiration of fuel decreases because of the small dimensions of the piston 3 and its small mass the allowable hertzian stress between the tappet roller 11 and the eccentric portion 9 of the camshaft 7 is not exceeded even at major accelerations of the piston 3 and high pressures during the pumping stroke in the exemplary embodiment shown in fig1 the control piston 15 is reinforced by a compression spring 31 which is braced against the cap 33 of the housing 1 in the second exemplary embodiment in fig2 there is no compression spring 31 and the cap 33 is embodied partly as a diaphragm directly behind the sealing seat formed by the shoulder 19 and heel 21 there is a recess 35 in the housing 1 which together with the suitably designed cap 33 forms a pressure relief chamber 37 the pressure energy stored in the pressure relief chamber 37 during the prefeed stroke reinforces the aspiration of fuel from the fuel chamber 29 into the pump cylinder 5 and thus reduces the tendency to cavitation during the intake stroke if the diameter of the sealing seat is less than the diameter of a receiving bore 39 in the housing 1 for the control piston 15 then the opening motion of the.