This paper presents the control system design and experimental results of the fuel-injection control system of a class of diesel engines. Based on an MCS-80C196KC microprocessor, the developed fuel-injection control system contains dual rack position measurement channels for both large range and high-precision measurements and has a cascade structure consisting of rack position and engine speed control loops. Using a decomposition-based robust/adaptive control method, high-performance rack position control is achieved in the presence of model uncertainties. An efficient mapping-based fuzzy proportional integral derivative (PID) control scheme is developed for the engine speed control in the absence of engine dynamics model. The proposed control system has been implemented on a diesel engine and experimental results have demonstrated high performance of the developed control system for all working modes of the engine.