The common rail fuel supply systems due to their flexibility of injection characteristics are the most frequently applied fuel supply solution in Diesel engines. The most essential parameters, which have the effect on the phenomena taking place in a Common Rail system are the duration of the injection, rail pressure and fuel temperature. There may also be other factors effecting the course of the injection. The split of the fuel dose into a few parts can cause a pressure fluctuation in the rail and also in the whole system, effecting the course of the injection. In the article tests results related with the influence of multiple injection on the total fuel dose and real onset of the injection have been presented. The tests were carried out on a test stand fitted with Bosch EPS-815 (electronic fuel dose measurement). For the testing of the real injection onset the visualization system AVL Visioscope was used. The control of the injector was realized through a controller which enabled to split the fuel dose into three parts.