The low flow rate and efficiency of existing grouting pumps such as piston pumps and diaphragm pumps result in difficulty in managing sudden water and slurry discharges. In this study, a new design for grouting pumps is proposed to improve the grouting flow rate and efficiency. A grouting model test scheme to manage the water inrush of a tubular karst is designed. The power consumption of this system is equivalent to that of a diaphragm grouting pump. Improved performance was also observed for the newly designed rotary piston pump in grouting plugging tests. The retention of slurry and changes in moving water flow are observed and recorded to examine the grouting effects of the pumps. In addition, the pressure and flow rate changes of the grouting slurry are used to gauge the performance parameters of the pumps. A rotary piston pump and a traditional piston pump were tested in single- and separate-hole grouting experiments in tunnel engineering sites. In the grouting model test, which manages the water inrush of a tubular karst, the newly designed rotary piston pump had a distinct advantage in terms of the slurry retention thickness and fracture sealing effect. In particular, the efficiency of the rotary piston pump increased by a factor of 10 over the diaphragm grouting pump. During the experiments in the engineering site, the grouting flow rate of the rotary piston pump showed significant increase when compared to the traditional piston pump. The construction time was halved. The proposed rotary piston grouting pump has shown obvious advantages over existing grouting pumps.