PUMP PLUNGER ASSEMBLY FOR IMPROVED PUMP EFFICIENCY

A plunger is provided for reciprocating inside the barrel of a fuel pump. The plunger has a proximal end and a distal end. The proximal end of the plunger includes a cavity that defines a depressed volume within the plunger. A volume filler is disposed in the cavity, where the volume filler is constrained in the cavity by a retaining element.