Gas feeding system for an internal combustion engine, having an improved pressure reducing valve

In a gas-supply system for internal-combustion engines, a pressure-reducing valve (7) is set between the reservoir (3) of the gas and a distribution manifold or rail (2) that feeds the gas to a series of electromagnetically controlled injectors (1) associated to the various cylinders of the engine. The pressure-reducing valve (7) has a piston member (220) that faces a chamber set downstream of a restricted passage defined inside the body of the valve in communication between the inlet connector (11) and the outlet connector (12). The piston member (220) is pushed by thrust means (62;80) towards a position in which it causes opening of an open/close element (210) that controls the communication between said restricted passage (14) and the inlet connector (11). The piston member is preferably provided with a single seal gasket that prevents leakage of gas towards the outside through the sliding coupling of the piston member within the respective guide bushing.