The thing I have found with 'pure' fluorocarbon lines is that you have to stretch them out before use, which can be a right pain.
Take your rod and reel and tie the end of the fluorocarbon to a firmly fixed point, then walk the line off the reel keeping it tight. When you get to the end pull it as tight as you can preferably walking back even further, then wind it back onto the reel.
It still doesn't cast as far as mono, but hopefully you have sorted out the problems of coiling.
I found the best compromise was a fluorocarbon coated mono or co-polymer line, P-Line Floroclear. It is still not the best casting line compared to mono, but it is OK