A filling nozzle of a fuel tank including a receiving pipe and a liquid-vapor separator, includes a hollow body communicating with an intake pipe for a stream of vapors from the fuel tank, an emptying pipe flowing into the receiving pipe, and a vapor outlet pipe. The hollow body includes a separation mechanism extracting droplets and including at least one wall movable between first and second configurations. In the first configuration the movable wall forms, together with walls of the hollow body, a maze in which stream of vapors passing from the intake pipe towards the outlet pipe is forced to circulate. In the second configuration the movable wall allows the stream of vapors to pass from the intake pipe to the outlet pipe following a path that avoids all or part of the path travelled by the vapors when the movable walls are in the first configuration.