1. Oil leakage 

Reason: The injection way of e-liquid is not correct; the e-liquid is too thin.

2. Suck the e-liquid into the mouth

Reason: The resistance is too small; the inlet hole is too large; cotton is soaked in  e-liquid for so long time.

The general reason: The e-liquid supply heating coil is enough, heating coil doesn’t consume fully.

Solution: Make the resistance bigger; change the inlet hole smaller; allow the atomizer to be insulated from the air, leaving the atomizer in a closed space.

Advice: shake or shake the atomizer more or less; take a few more breath; don't fill oil fully and suck hardly.