When I tie a knot with my fluorocarbon line it curls up and becomes unusable.

I wet the line and tried a couple of different knots but still have the same problem.

Is there a specific knot I need to use? What am I doing wrong?

Pull the tag line first. For knots like clinched and improved clinched move your knot down first be for pulling the tag end.

I use the Trilene Knot and the Uni Knot, both are working good with fluoro. What brand of line are you using? 

I am using p-line 8 lb.

Tighten your knots slowly and use plenty of spit.

6 minutes ago, Jrob78 said:

Tighten your knots slowly and use plenty of spit.

I agree, I find my line "curling" when I don't use enough saliva. 

fluoro just can't be wet enough when you tighten it down!  agree with above on pulling the tag end first.

What type of knot are you trying to tie?

I started using the San Diego Jam knot last year and will not be going back anytime soon. I think its easier than a palomar knot and I can tie it faster with just as much confidence. I think when you are tying your knot, you are burning the line making it curl, don't cinch it before your tag end is tighter if you want to keep tying the palomar. 

Like the above posters, make sure you slobber on the line before starting and several times during the knot tieing process.

The "curling" means you've just stretched/burned your line and created a weak spot.  Use saliva for lube, and be cautious about which end to pull first to cinch the knot down before tightening it.

San Diego Jam, plenty of saliva, tighten it slowly and smoothly. 

You tube best fluorocarbon knot Shaw Grigsby...

I use the improved clinch and wet the heck out of the knot, slide the knot down to lure then slowly tighten.