Method and device for the diagnosis of gaseous fluid leakages in a fuel feed circuit of an engine driven vehicle

A method for the diagnosis of gaseous fluid leakages in a circuit injection-feeding gaseous fuel into each cylinder of a vehicle internal combustion engine (M) by means of an injector (5), said circuit comprising, in addition to a tank (2) for said fluid under pressure, a reducer member (1) for said pressure disposed in a line connecting said tank to the injector, a controlled valve member (4) and a pressure measurement device (6), said components (4, 5) being connected to a command and control unit (8), said method comprising closing the valve member (4) and each injector (5), and evaluating the pressure of the fluid in the line by means of said measurement device (6) in order to determine possible leakages. The evaluation is carried out during the acceleration phase. A device for implementing this method is also claimed.