The mysterious disappearing fuel leak

HEy allfirst, the parameters: yesterday I took my bike (96 cBR 900 ) out of storage in the shed, where it spent last winter and summer.I'm in Canada, winter is very cold and summer is quite humid, but the bike was sealed in a enveloppe of several layers of plastic film, (taped shut) with dessicant pouches added.So the bike had to go through major temperature changes but no major humidity. Before storing it last year, I let it run with the fuel line off and emptied the carbs.There is gas in the tank.I get the bike idling without a problem, then it starts to leak fuel at some point, not a minor leak, it's really dripping fast, there's a small puddle forming under the bike.I didn't see it start, I noticed after a while. Switching the fuel line off stops the leak, back on, it leaks again.Today I setup to remove the tank, and tried the same thing, with the tank unscrewed and set ajar to see clearly what's going on...no leak at all. I let the bike run for 3 or 4 minutes, nothing. Should I let it run longer? can it be the carbs' seal ? why the delay? help ! thx :)edit: tomorrow i'll try it in the alley, we'll see .Thank you gents. via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/d580vo/the_mysterious_disappearing_fuel_leak/?utm_source=ifttt