a fuel injection system for an internal combustion engine including a fuel injector which can be subjected to fuel at high pressure and is actuatable via a metering valve device by which the pressure in a pressure booster control chamber is controllable such that the pressure in a pressure booster pressure chamber , defined by a pressure booster piston , that can be filled with fuel from the high - pressure fuel source via a filling path in which a check valve is disposed and that is in communication with an injection valve member pressure chamber , is increased by the pressure booster piston such that an injection valve member opens for injecting fuel , whereupon fuel is positively displaced out of a damping chamber via a damping path , in which a damping throttle is disposed . to assure stable injection performance , the damping path is embodied such and connected in such a way to the filling path that the fuel positively displaced from the damping chamber via the damping throttle in an injection event reaches the filling path of the pressure booster pressure chamber via the damping path .