Fault diagnosis device for fuel evaporation/sublimation-prevention system, has first and second diagnostic devices and fault diagnosis region, assesses restored pressure values to detect abnormality

摘要

The device has a first diagnostic device for comparison of a restored pressure with a fault diagnosis region at reduced pressure with decision values and a second diagnostic device for measuring a second restored pressure with the diagnosis region closed at atmospheric pressure if the first pressure exceeds either decision value and comparing the second pressure with further values. Restored pressure values are assessed to detect an abnormality. The fault diagnosis device has a first diagnostic device for serial comparison of a measured restored pressure after a fault diagnosis region of the system is brought into a reduced pressure state with first and second decision values and a second diagnostic device for measuring a second restored pressure by closing the fault diagnosis region after atmospheric pressure has been introduced if the first restored pressure exceeds the fist or second decision value and comparing the second value with third or fourth decision values. The restored pressure values are assessed to detect an abnormality.