Hi Minolaw,
These are a top feed coil so flooding is quite uncommon, they usually suffer more with dry hits.
When you fill up, are you ensuring you arent spilling any in the centre hole?
Is your juice a high PG ratio?
If so, do you have a variable voltage device that would allow you to crank up the voltage and burn more juice?
If you want to stay with the same size clearomizer I would recommend having a look at the iClear 16s, never let me down while I was using them!