The development of the advanced cryogenic liquid-propellant engines (LPE) for rocket space systems (RSS) may require a wide range of autonomous tests of combustion chambers (CC) and gas generators (GG) in experimental units (EU) with pressure and pump feed systems (FS) of propellant components (PC): to be conducted. The article deals with the experimental units with turbopump assembly (TPA) having recirculation and closed circuits and various feed circuits for the gas generator turbine drive unit. Recommendations on startup stabilization and test conditions have been developed by the authors. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.