This paper addresses a control scheme for a parallel hybrid vehicle powertrain by introducing fueling control techniques. Since a diesel engine is involved in the proposed configuration, the control of fuel injection mass and timing becomes a crucial issue. In this study, these two variables are selected as control inputs for the hybrid powertrain system. Meanwhile, an optimization-based control strategy is designed to solve the hybrid electric vehicle power management problem by incorporating engine brake specific fuel consumption characteristics with regard to fuel injection control variables. To show the advantages of the proposed control scheme, another optimization-based strategy with fixed fuel injection timing is developed and implemented for comparison. The influence of NOx emission is also considered in control strategy and simulation results to show that the proposed fuel control technique has limited impact on NOx emission but imposes a considerable improvement on fuel saving.