The paper analyzes the changes in an LPG injector flow mass characteristics when input pressure is altered. The research was carried out at a test stand with an air-supplied injector. The test results (the pressure both before and behind an injector, a control signal and the current flowing through an electromagnetic coil) were analyzed for the impact of pressure on the injector characteristics. The analysis deals with a pressure effect on a unit mass flow, injector opening dead time (minimum time of a signal that causes an opening), the characteristics linearity, and its intersection point with a time axis. There was also analyzed a single injection time course, particularly emphasizing injector valve opening and closing time. It has been stated that the increase in pressure results in the increased unit mass flow and the simultaneous increase in injector dead time as well as a shift of the intersection point with a time axis along this axis.