In one aspect of this invention, control systems (100) are provided for controlling the inflation of a tissue tensioner or balloon for a fluid delivery system, such as for a needleless fluid injection device. In another aspect of the invention, a system for reducing the response time for jet injection of fluid is provided (200). In yet another aspect of the invention, systems and devices are provided for controlling the volume of fluid that is ejected from a fluid injection system, which systems include at least one stop (410) that is selectively rotated to limit the movement of a shaft (402) in a linear direction, thereby controlling the amount of fluid that is ejected from the system.
