An auxiliary carburetion device in direct fuel injection engines, to be positioned in correspondence with a main duct (12) feeding air to the engine crankcase (10), a throttling member (38) being located in the main duct (12). The device includes a block (13) containing at least one selective regulating element (15, 25) positioned in a connection duct (19, 20; 30) which is connected at one end to a vessel (14; 45, 51) containing a constant predeterminable amount of fuel and to a mixing air duct (23, 32), and at the other end to the main duct (12) feeding the crankcase (10).