A fuel is conditioned in a fuel supply system for more efficient combustion in a combustion chamber. The conditioning system includes a plurality of vessels, each defining a fuel chamber for fuel conditioning, at least one fuel dispersing nozzle mounted for discharge into the fuel chamber, at least one gas inlet port, a gas outlet port with a gate valve and a pressure reducer mounted thereon. A low level sensor registers a low level of conditioned fuel in the fuel chamber. A gas source feeds a gas to the vessels wherein the gas is dissolved in the liquid fuel for forming a liquid/gas fuel solution. A gas delivery and gas pressure control system with flow-directional valves and gas pressure regulators supply gas and maintain a relatively high, first gas pressure P.sub.1 and a relatively low, second gas pressure P.sub.2. A low-pressure fuel pump and a liquid fuel supply line supply liquid fuel from a fuel reservoir to the at least one dispersing nozzle of each fuel chamber at a third pressure P.sub.3 higher than the first pressure P.sub.1. A high-pressure fuel pump feed the conditioned fuel to a combustion chamber at a fourth pressure P.sub.4 that is higher than a pressure in the combustion chamber at a moment of combustion. Finally, there is provided an electronic control system connected to receive a signal from the low level sensor and for switching the gas delivery and gas pressure control system over from the fuel chamber indicated by the sensor as depleted to supply the conditioned fuel from another, filled-up fuel chamber.