A pulsed detonation combustor was developed with the total absence of mechanical valves. The device was operated over a range of conditions with air and gaseous fuels (ethylene and propane) with both fuel streams and airstreams operating in valveless mode. This configuration allows a simplified design that could be used for propulsion and power generation systems as well as combined-cycle propulsion concepts. High-frequency pressure instrumentation reveals that overdriven detonations and Chapman-Jouguet detonations are generated within the device using both fuels. A novel vortex-generator design is employed to promote the deflagration-to-detonation transition process in a cyclic fashion. Pressure instrumentation within inlet manifolds confirms the capabilities of the configuration to cease fuel and air flows over a portion of the cycle. The character of wave development in the device is discussed, and a performance map is included to denote the range of operation in valveless mode.