account with the aid of a correction term a drive time of the injectors is determined with the aid of a corrected pressure so that a desired fuel quantity is injected the correction term is determined with the aid of a least squares estimator that estimates the injection pressure at the nozzle of injector as a function of the geometrical data of the system in particular a length of the lead from the rail to the injector and physical boundary conditions for example a fuel temperature application_number US 66358700 A description in all the figures of the drawing sub features and integral parts that correspond to one another bear the same reference symbol in each case referring now to the figures of the drawing in detail and first particularly to fig1 thereof there is shown a schematic configuration of a fuel injection system for a direct injection internal combustion engine as it is used under the designation of a common rail system chiefly in motor vehicles having a diesel internal combustion engine in the injection system fuel is taken in by a predelivery pump 12 from a fuel tank 10 via a fuel line 11 the predelivery pump 12 delivers the fuel via a fuel filter 13 to a high pressure pump 15 which compresses the fuel and feeds it into a high pressure reservoir 17 under high pressure in order to be able to set a volumetric flow of the high pressure pump 15 into the high pressure reservoir 17 in accordance with the respective operating conditions of the internal combustion engine as required there is disposed in the fuel line 11 between the predelivery pump 12 and the high.