Evaporative system and method of diagnosing same

A method of diagnosing an evaporative system, comprising the steps of:

• opening a purge valve, provided on a line connected between said evaporative system and an intake tube, in a closed condition of a drain valve connected to a canister;
• subsequently detecting a pressure in said evaporative system;
• subsequently closing said purge valve when said detected pressure reaches a predetermined value;
• subsequently detecting a pressure in said evaporative system in a closed condition of a gauge valve for generating a standard leak between the evaporative system and ambient air, and detecting the pressure in said evaporative system in an open condition of said gauge valve, so as to detect leakage of the evaporative system;
• and performing a diagnosis of said evaporative system based on a differential pressure with respect to ambient air and a pressure change corresponding to said detected pressures in which, first, the pressure in said evaporative system is detected in the closed condition of said gauge valve, and then the pressure in said evaporative system is detected in the open condition of said gauge valve, the pressure in said evaporative system is pulled down to a predetermined pressure, the pressure in said evaporative system is detected, this operation being performed a plurality of times, and a diagnosis of said evaporative system is effected based on the detected pressure in said evaporative system.

A method of diagnosing an evaporative system, comprising the steps of:

• detecting a generating amount of an evaporative gas within said evaporative system;
• opening a purge valve, provided on a line connected between said evaporative system and an intake tube, in a closed condition of a drain valve connected to a canister;
• subsequently detecting a pressure in said evaporative system;
• subsequently closing said purge valve when said detected pressure reaches a predetermined value;
• subsequently detecting a pressure in said evaporative system in a closed condition of a gauge valve for generating a standard leak between the evaporative system and an ambient air, and detecting the pressure in said evaporative system in an open condition of said gauge valve so as to detect the leakage of the evaporative system;
• and
• performing a diagnosis of said evaporative system based on said detected pressures and said evaporative gas generating amount.

A method of diagnosing an evaporative system, comprising the steps of:

• introducing a negative pressure to said evaporative system in a closed condition of said evaporative system;
• detecting a pressure in said evaporative system in a closed condition of a valve for generating a standard leakage between the evaporative system and ambient air, and a pressure in said evaporative system in an open condition of said valve;
• and
• performing a diagnosis of said evaporative system based a differential pressure with respect to the ambient air and a pressure change corresponding to said detected pressure at a time of opening said valve and at a time of not opening said valve.

A method of diagnosing an evaporative system, comprising the steps of:

• detecting a generating amount of an evaporative gas within said evaporative system;
• introducing a negative pressure to said evaporative system in a closed condition of said evaporative system;
• detecting a pressure in said evaporative system in a closed condition of a valve for generating a standard leakage amount between the evaporative system and ambient air, and a pressure in said evaporative system in an open condition of said valve;
• and
• performing a diagnosis of said evaporative system based on said detected pressures,
• wherein a diagnosis of the evaporative system is performed on the basis of the detected pressures and said evaporative gas generating amount.