A vehicle fuel system has on-board diagnostics for leak testing with correction for different temperature variations arising in an evacuation phase. Pressure is measured at intervals during the evacuation phase and a correction is made to the loss of vapou...

A vehicle fuel system has on-board diagnostics for vapour integrity testing. The vapour integrity test includes evacuating the fuel system; closing the system and allowing pressure to rise due to air ingress and vapour generation (bleedup) ; making a serie...

A highly accurate diagnosing apparatus for an evaporation purge system, which is not so easily affected by fluctuation in an atmospheric pressure. An evaporation system including a fuel tank is set in a pressure state different from an atmospheric pressure...