I just answered a guys post in the new member area. He wanted to know how to get rid of the the burnt taste in his 510. I discovered the magic answer to 510 maintenance and it sounds like you may benefit as well so I'm just going to copy/paste the same reply here.
Same thing happened to me about a three days into having my 510. A couple points I'll add that fixed it for me. First off once this happens remove your cartridge and smell it. You'll notice that that burnt flavor has now polluted your filler and cartridges as well as atomizer. Dripping takes it away temporarily but then your back down to the polluted junk. Here's what fixed the problem for me:
1)Don't just blow out the atomizer it needs a thorough draining to get rid of the "yuck". To do this twist a paper towel up and push gently into the atomizer till it touches the wick. Leave it to sit over night with atomizer up, paper towel down (draining position). If you want it done in a hurry replace paper towel every 5-10 minutes until you pull out a paper towel that is perfectly dry. Your atomizer is now completely drained. IMPORTANT: Add 5 drops directly to atomizer prior to
vaping again in order to prime it.
2) Your cartridges have the same "yuck". Remove filler (wool I guess). Wash the wool and cartridge itself thoroughly in hot water.. Do so until you get no burnt smell on either. Blow water out of carts and dry wool on paper towel.
3) To avoid this happening again: Make sure to align your cartridge correctly (I'm not sold that this is all that important but it does seem to help a bit). To do this look in side your atty and you will see a white ring at the base of the wick that is the same shape as the top of your cart. Match em up when you plug it together.
Personally I am now in the habit of doing this as routine maintenance as it made a huge difference!!! Every few nights I simply yank the wool out of all my empty carts run to the sink and wash/dry. Stuff a paper towel in at least one of my atty's and prop it up in position for the night. Takes 5 minutes and is so worth it!
In regards to getting 10 smokes out of a cart. Sounds about right to me if filled properly. Are you simply dripping into the cart until wool is saturated? If so....wrong answer. Pull the wool and drip 13 drops into the empty cartridge....gently replace wool with tweezers...then top off until liquid will not absorb. 10 smokeys ready to go. Again something that becomes second nature quickly as rather than count drops you'll just know where your "fill line" should be.(I would imagine exactly how many smokes it equates to would also depend on your
e-liquid. I use Like Smoke/Ruyan #4 in 24mg)