I went thru a lot of Nautilus coils, but only because I used 5 of the tanks with different juices and vaped heavily for months with them.  The only time I got a dry hit was when I wasn't paying attention and let the tank run dry.
When I swapped out a coil I would change the coil and fill the tank.  Then with the tank I would cover the air holes with a finger and take a few good draws WITHOUT POWER to create suction and pull the 
juice into the wick.  After each draw I would check to see the air bubbles from the wick holes.  I repeated this process 3 or 4 times.  Then I usually let the tank sit for 5 minutes.  It worked for me.
It's possible you have gotten some bad coils.  I never "cleaned" my coils until they were gunked up.  Even when swapping 
juice I would clean the tank and just use a paper towel to wipe off the bottom part with the coil.  Usually after 3 or 4 hits with the new filled tank the old 
juice flavor disappeared as the new juice was wicked into the coil.  I would still take a few unpowered draws for prime to be on the safe side.
After a coil got "gunked up" I would take it and put it in a small glass jar with some vodka and let it soak for a few days to a wee, giving the jar a shake every now and then.  Then I would take the coil out, blow it off and let it air dry for a day as the vodka evaporated.  It didn't make the coil like new but I did get a lot more mileage out of them.  The Nautilus coils can be rebuilt/coiled, check you tube if interested.