Monitoring the fuel injection system of dual fuel engines

During the liquid fuel mode of a dual fuel internal combustion engine (10), soot may deposit at the fuel injectors (30, 42) and may jam the fuel injector needle. In such case, the liquid fuel supply system (32) may not work properly. For evaluating the mechanical function of the liquid fuel supply system (32), a common rail (34) fluidly connected to the liquid fuel supply system (32) may be monitored. In case of a mechanical malfunction of the liquid fuel supply system (32) or of the ignition fuel supply system, the dual fuel internal combustion engine (10) may be switched over from LFM to GFM, respectively.