Eddie,

If you're using a high pressure bladder and not using any kind of pressure reducer before the needle valve then you are probably experiencing a venturi effect that is sucking in air around the o-ring and threads. Some RNV can do a better job then others at not doing that. Appearently yours can't handle the high pressure directly. If you don't want to use a pressure reducer before the RNV then you might use the RNV that came with the OS 15LA. It doesn't seem to be affected by being fed the high pressure fuel directly into it. Lou had the same problems you described because he doesn't use a pressure reducer and so he simply uses the original LA RNV after it's been cut off the backplate. I believe that he tie raps it behind the engine. You can read Lou's discussion about the problems he had at his web site [link=http://www.georgiacombat.com/]GeorgiaCombat[/link] . If you want to continue using your Fox RNV then make yourself a pressure reducer. You'll find a simple one to make in my article on using bladders in the workshop section of my web site [link=http://www.texascombat.com]TexasCombat[/link] . I've never experienced the problem and I use the OS replacement RNV that Lou was having problems with, but I use a pressure reducer on my system.