Pump injector

The pump-nozzle unit for the injection of a medium, especially fuel, includes a pump (2) with a piston (3), and a pressure chamber (5) hydraulically connected to a nozzle chamber (11) via a pressure channel (6,9). The pump interacts with a control valve (7), and between the pressure channel and control valve a pre-control volume is formed and which is hydraulically connected to the pressure channel via a restrictor (23) so that a change in the closing position of the control valve is transmitted to the pressure channel in a damped state.