just so you know I put a new cartomizer from my 5 pack into a larger tank (VPX Cartomator from NHALER) than the f16 and primed it perfectly by filling the tank, plugging the bottom hole, sucking almost a whole tanks worth of liquid inside the carto until I get a slight gurgle. (this takes a while) Then I let it sit over night or 12+ hours. When I started vaping it the next day it was borderline flooded because it was gurgling a bit, but a few puffs later and until this day it has hit perfect every time!!! It may be a task to prime these things but when you do it right, you will know what all the rave is about with these devices. They just simply work when they are set up. I have also noticed that the filler under the driptip is white so I figured it was going dry (taste was fine though) put 1 or two drops to top it off and it flooded. So dont be fooled it is definately wicking enough down there. Hope this helps. I think a major part is that it is tight inside the tank and properly primed.