A fuel injector for a combustion engine includes an injector head including a nozzle, a premixer, and a distributor structured to distribute a plurality of different fuels to different sets of fueling orifices in the premixer. A pilot assembly of the fuel injector is coupled to the premixer and includes a first fueling passage for a first fuel and a second fueling passage for a second fuel. Multiple sets of fueling orifices are positioned within the fuel injector, the fueling orifice sets being selectively connectable to a plurality of different fuel supplies, and both located and sized so as to accommodate a wide range of flow rates to enable a combustion engine coupled with the fuel injector to operate on fuels having a range of Wobbe indices and compositions.