A fuel injection system with a fuel injection pump (1) is disclosed. The system has a first correction device for correcting a first base volume (V') of fuel which is fed by the fuel injection pump (1), using a correction value which is corrected in order to realise a predetermined constant engine speed at least during a predetermined engine operating state, a calculation device for calculating the change in the correction value in accordance with the fuel temperature (Tf) given a predetermined engine load in the predetermined engine operating state, and a device for determining at least one property of the instantaneous fuel on the basis of the change. Accordingly, the system can automatically detect the properties of a fuel during driving. <IMAGE>
