The invention relates to a fuel injection pump for internal combustion engines having a simultaneously reciprocating and rotatihg pump piston serving as a fuel distributor. The fuel quantity is delivered by the pump in dependence on engine rpm. For this purpose, the fuel delivery may be interrupted by opening a first relief channel, connected to the pump working chamber, by means of a fuel quantity regulating member. The pump also includes a second relief channel connected to the pump working chamber which is first opened by the pump piston and then closed again after a predetermined delivery stroke has been executed.
In a known fuel injection pump of this kind, the delivered fuel quantity is regulated by opening a first relief channel connected to the pump working chamber by means of a hydraulically driven reciprocating regulating member operating on the principle of a so-called "fluid stop." In order to achieve a load-dependent shift of the onset of injection to a later time when the load decreases, this system is provided with a second relief channel which is so controlled by cooperation of an annular groove on the pump piston and an annular groove on the regulating member that the second relief channel is first opened and then closed again by the annular groove on the pump piston; the opening occurring earlier when the "fluid stop" is rising corresponding to a decreasing injected fuel quantity or decreasing load. An injection pump of this type is very expensive and requires substantial changes in the body of the pump so as to realize the described regulation process.