Before you give up on your cartos (especially if you have a bunch at hand already)...try this filling method.
http://www.e-cigarette-forum.com/forum/general-e-smoking-discussion/200782-cartomizerfillinator.html
Be sure to blow through the carto good (back into the bottle maybe) and wipe before screwing it on your battery.
It's worked wonders for me in making sure the filler is well saturated and there aren't any dry/air traps in it. Often times it's that 'first fill' that just doesn't want to soak in good...this method of filling seems to takes care of that for me.
If it vapes great for several hits at first fill then goes dry...
You can try giving the carto a shake or tap from time to time (like packing your old analogue ciggies). If you use a neck lanyard, just give it a spin or two every now and then. Or as mentioned before, thin the liquid a little with distilled water, vodka, or PGA.
I've used the method for 808-D1, Regular Boges (and other vertical coil cartos), and of course the Dual Coil cartos.
I've also had good luck with thick liquids in the
801 type atomizers and their
native carts. You'd need a
901/808>801 adapter for this. You can also drip in these FAT atties and they do a very nice job (extra large bridge holds nearly twice as much as a regular 510 or 901 atomizer). 801
drip tips are a little bigger, so you might want one if you plan to drip in the 801 (be careful if your batteries are autos).
Given your battery type, the 801 would make it look something like an ink pen instead of an e-cig. You'd probably drain the battery before you emptied the cart, as I can get a good hour from a single fill constantly vaping at high voltages.