The 510 atomizer uses more liquid than the normal wicking action on the cart is capable to provide (IMO)
You have some options.
1- Take 2 or 3 drags and wait... let it wick for a few minutes and repeat.
2- Keep topping... the bad is it will only take a couple of drops each time. (no look here with the straw or the PTB. I am using polyfill from Walmart.
3- Drip! For me, it's only a drop each time. More than that will flow the atomizer.
The 510 provides a great Throat hit and lots of vapor... only when you know how to find the sweet spot between a dry cart (burnt taste) and a flooded atomizer (no vapor, no hit, gurgling sound)
Be sure to have fresh batteries! Sometimes, when all of the above is OK... the battery is weak...
rinse...
repeat...