The invention concerns a fuel dosing device (10) for a fuel injector of an aircraft turbomachine, comprising an opening (24), a movable member (28) for sealing the opening, and elastic return means (60a, 60b), the member being capable of moving under the effect of the fuel pressure. The device (10) comprises a first outlet (10a) communicating with a primary circuit (12) of the injector and a second outlet (10b) communicating with a secondary circuit (14). Moreover, it is designed such that, up to a defined level of displacement of the sealing member, the latter allows the fuel coming from the opening (24) to reach the first outlet (10a) and, only beyond the defined level of displacement, the member allows the fuel coming from the opening (24) to reach the second outlet. The device (10) further comprises a hollow outer body (20), and a hollow intermediate body (22) housed in the outer body (20), said opening (24) being made in said intermediate body provided with a seat (26) for receiving the sealing member (28). The sealing member (28) is housed slidably movable in said intermediate body (22). A fuel flow space (30) is provided between the intermediate and outer bodies (22, 20), the intermediate body being provided with orifices (32) for the fuel to pass from the inside of said intermediate body (22) to said fuel flow space (30), said flow space communicating with said first outlet (10a). A secondary opening (46) for the fuel to pass through is provided on the intermediate body (22), the secondary opening (46) being intended to be sealed by the movable member (28) provided it has not reached said defined level of displacement, and intended to be opened when the movable member (28) is between the defined level of displacement and the maximum opening position of same, said secondary opening (46) communicating with said second outlet (10b).