if i had to guess on the limited information i would say probably a hot spot. one particular spot is probably getting hotter than the rest and burning the crap out of your
juice right there. that video posted is great info. when you get the coil hooked up, start at the lowest voltage and pulse fire it dry and mess with the
coils until you get all coils glowing evenly. jump it .2 volts, repeat, jump .2 volts, repeat, etc. go up to like 4 or 4.2 volts until its good then fill and enjoy