Is it from
fasttech by chance ? I've had the same problems. Folks will tell you to check all the seals....clean the seals....make sure the head is screwed in all the way,make sure its 30% or more full, don't suck too hard. If your like me, you've tried all of that. If it is a
fasttech evod , and or their replacement
coils/heads, Ive hsad issues with those heads being poorly threaded, short threaded, and the seal that covers the coil is not seated correctly ( you can fidget with that seal and make it work some times.
If its not a FT Evod, sorry about the post here..... If its a real one, I don't know. I've sworn off FT Evods and the replacement heads.
My two cents... ( have 5 FT Evods between 3 users and ordered 15 heads.. Just not much luck.)
Hundreds of folks here on the forums absolutely LOVE the real ones.