a fuel injection pump for internal combustion engines , which has improved and simplified means for a throttled preliminary shut - off to prevent cavitation in the injection system and late injections by the fuel injection valves . the pump piston is provided with two recesses that terminate in chamfered control edges and control the end of the delivery cycle and also contains a throttle bore , which has a cross bore , and connects the first recess , which is opened shortly before the other recess , with the pump operating chamber by means of a longitudinal bore in the pump piston . the second recess has an unthrottled connection to the pump operating chamber .