A method facilitates vaporization of a fuel in a direct-injection four-stroke engine including at least one cylinder with a combustion chamber, at least one fluid intake with an intake pipe and a valve, at least one burnt gas exhaust with an exhaust pipe and a valve, a valve controller and fuel injector. The method includes, in the vicinity of the intake phase start, in opening the intake valve so as to allow the intake fluid into the combustion chamber, in opening exhaust valve so as to feed again into this chamber at least part of the burnt gas contained in exhaust pipe; prior to the end of the intake phase, in closing the exhaust valve; in the vicinity of the intake phase end, in closing the intake valve; and during this intake phase, in carrying out at least one fuel injection into the combustion chamber.