A gurgling sound is from a mixture of air and e-juice in the cartomizer, most likely in the center air hole. When you blow through this air hole to clear it of liquid, be sure to
turn the tank upside down so that the wicking holes in the cartomizer are in the air portion of the cartotank. Blow through the drip tip end and catch any juice forced out with a paper towel.
Blowing with the tank right side up will allow additional juice from the tank to be sucked into the cartomizer, as the wick holes are in the juice portion of the tank. NOT what you want. Make sense?
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I don't know what method you used to pre-fill the cartomizer, condom or top drip method, but it doesn't matter. Both work as long as you do it correctly. I happen to prefer the top drip method with some personal modifications. I use a wood tooth pick to plug the center air hole - no need to blow the tank out with your mouth. I also drip and shake (like a thermometer).
Fill the tank with both tank caps on the tank, and drip juice in through the opening of the top cap (and the carto half way in the tank). It's all explained in this cartotank tutorial I wrote (with accompanying video demo).
http://www.e-cigarette-forum.com/forum/blogs/baditude/3710-5-cartomizer-tank-setup.html
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Incorrect vaping technique can cause the carto to flood. Too hard and short of a draw will cause too much juice to enter the carto from the tank. Take longer, gentler pulls of 4 - 6 seconds length. Think of a straw in a thick milkshake.
Hope that helps.
