A prototype high pressure common rail fuel injection system was designed and tested on single and two rotor rotary engines. Performance of previous experimental pump-line-nozzle-gearbox fuel injection systems was matched at the cruise power conditions, and improved upon at other operating conditions. The high pressure common rail system provides electronic control of fuel injection timing, fuel delivery, and peak fuel injection rate. The instantaneous fuel flow rate during injection can be modified by mechanical adjustments to the system. Unusual features of the system are the high injection frequency achieved (8000 injections/minute/injector) and the use of a pilot injector. The reliability and safety of the injection system design are primary considerations because the system is intended for use in an aircraft engine.