A fuel device including a high-pressure fuel source from which fuel is supplied to fuel injection valves. The fuel injection valves are controlled with the aid of a valve that is driven by a piezoelectric or magnetostrictive drive mechanism. With the aid of this drive mechanism, a 3-way valve having a closing body can be adjusted in an intermediary position in which a control chamber, by way of which a hydraulic force can be exerted in the closing direction on a valve closing member of the injection valve, can simultaneously be connected to a high-pressure fuel source and a relief chamber in order to adjust a control pressure that lies between the high pressure of the high-pressure source and a relief pressure. In this manner, a partial opening of the injection valve member of the injection valve can be adjusted in order to introduce a reduced injection quantity into the combustion chamber of the internal combustion engine.