Fuel vapour take=off system of motor vehicle IC engine - designed for introduction of fuel vapour which is vaporised from fuel contained in engine fuel tank in to engine inlet duct across discharge valve.

摘要

A control unit(10a) is provided e.g. a microprocessor, with a storage memory, for the diagnosis of the fuel vapour discharge system related to the occurrence of a non-normal condition. A pressure sensor(11) determines the pressure inside the fuel tank(4) and the pressure signals are fed to the control unit. A discharge value control unit controls the opening of the discharge valve(9) over a first predetermined time interval, if the engine is in a stable operating condition. A diagnostic unit carries out a determination related to the occurrence of a non-normal condition in the fuel vapour discharge system. The diagnosis is carried out on the basis of the size of an alteration of pressure inside the fuel tank, over a second predetermined time interval, which covers the first predetermined time interval. ADVANTAGE - Alerts driver to existence of non-normal condition in engine, so that this can be attended to, to avoid discharge of fuel vapour to atmos.