Actually guys, its not an empty fuel filter, its an ONFA fuel filter and primer installed between the tank and exhaust.

[link=http://www.rcuniverse.com/forum/m_4462148/tm.htm]Read this thread completely to get the whole story!!!![/link]

BTW: Once you fit the valve you will have to retune your engine(lean out the high side alot, I think I had to turn mine in like 3.5 full turns. And then lean out the low side to control the idle/low end circut)