Draining the gas tank at a fast rate will induce POOGS like conditions, since the vent in the gas cap is very small. So small in fact as to not keep up with the sudden displacement of the quickly exiting fuel. You would need to drain the tank at a rate that the gas cap vent can compensate for to validate the gas cap vent function using this method. That could take a while. However, it only takes about 15 minutes to disassemble the gap and flush the vent line. I would redo the gas vent system clean to be sure. Another testing method is to attach a small vinyl tube to the nipple on the base of the gas cap (vent opening) and gently force air in and out of the gas cap. Remember that the vent is very small, but you may be able to induce the hissing sound (HISSING IS GOOD)! Flush the vent line using carb cleaner or non-chlorinated brake cleaner.Another reason I thought there was a vent problem is that I was draining the tank into a bucket the other day when the fuel flow pretty much stopped. Thinking the tank wasn't empty, I opened the cap and the flow resumed until the tank was empty. That's what compelled me to remove the cap and check the venting per the forum advice. When the problem occurred on the last ride I thought there must be something I'd overlooked.