Hydromechanical regulator for controlling the flow of fuel injected into a turbomachine by means of a fuel feed unit (10), comprising a tachometric balance (20) having a beam consisting of two arms (24, 26), which beam can move about a pivot pin (22) under the action of at least a first force F1 applied by a drive rod (18) of the fuel feed unit via a first elastic member (28), and a rod (36) associated with a drive piston (38) for applying, via a second elastic member (40), a force F4 opposing the first force F1 to the beam of the balance so as to cause the fuel feed unit to open further during the transition from a first engine acceleration law to a second engine acceleration law.