Unfortunately many mechanics just don't understand how this system works. The smoke testing is just part of the diagnosis as that will check for external leaks. However, this system can still leak internally. Basically the large leak code is telling you that the system is not building pressure like it is supposed to do. I attached a lot of info on this system but it needs to see the proper pressure in the system with the purge valve closed. If it does not see the pressure build then it sets this code.
More then likely the purge valve is leaking or the Close valve is leaking. If both of these are closing and sealing then the only other exit point for the pressure is the gas cap. So if you already replaced that then that leaves the close valve or the purge valve solenoid. The way to test this is to remove the line from the purge solenoid and hook up a vacuum pump and pull the system into a vacuum. If it holds a vacuum then the leak is the purge valve. If not then you have a leak somewhere else in the system.
The fact that he did not find smoke coming out anywhere is why I think the purge valve is the issue because the smoke would go into the engine. Did he remove the oil fill cap when smoke testing it? If so, he should have seem the smoke coming out of the engine if he ran it long enough. Let me know if you have questions and we can go from there. Thanks
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Friday, July 31st, 2020 AT 5:09 PM