Lets assume the cart isn't dry and is working properly.
Here is a tip a lot of us on here reccommend.
At night before you go to bed, disassemble your e-cig, put the battery on to charge, and place the atomizer on a paper towel with the cartridge end facing downwards. Personally I stand my atomizers in a small glass with the cartridge end facing downwards.
What might have happened is that you have flooded the atomizer with the new very juicy cartridge you put in it and left overnight.
Here is how to hopefully fix the problem, take it apart, take the atomizer only and a paper towel, hold the paper towel on the end the cartridge goes in and then blow gently into the end that the battery attaches too. You should see an amount of
juice soaking into the paper towel. Continue doing this until there is only very little or no more
juice on the paper towel.
Put the e-cig back together, preferably with a fully charged battery, check the cartridge, if it looks at all dry, use a new cartridge. Leave it for 5 minutes and then try smoking it again.
It will take several puffs on it before the amount of vapour is back to the right level.