Fuel injection pump

Claim 1

In a fuel injection pump of the type having two sets of plungers commonly rotatably displaceable and having metering grooves for cooperating with a pump port such that the plungers of one set cease supplying fuel to their associated engine cylinders during idling of an engine, whereas the plungers of the other set supply fuel to their associated cylinders during idling of the engine, the plungers of each set having a generally helical metering groove formed in the cylindrical surfaces thereof, and a longitudinal groove in the cylindrical surface communicating said metering groove with the upper end of the plunger and hence with the pump chamber of the plunger, the longitudinal grooves in the plungers of said one set being relatively enlarged in width relative to the longitudinal grooves of the plungers of said other set such that rotation of the plungers brings the longitudinal groove of each plunger of said one set into a non-pumping relationship with its pump port when the plungers of said other set are in their engine-idling fuel delivery positions, and a cut recess at the intersection of the longitudinal groove and the helical groove of each plunger of said first set, each said cut recess extending at a right angle to its longitudinal groove between the cylindrical surface of its plunger and the opening of the recess into its longitudinal groove, the upper end of each said recess being closed, the lower end opening into said helical groove and the floor of each recess being oriented such that the depth of the recess increases toward the longitudinal groove.