take the needle out and put a small peice of fuel tubing on the neadle and put the neadle back in, sometimes air will leak around the neadle threads. the plastic neadle valve body could have a small crack in it also. New fuel line all the way around, even the tank gets new line. I had a 6 oz dubro tank on a plane and the factory tank line that goes inside wasn't limber enough and it wouldnt flex enough to get to the bottom or in inverted flight it would go to the top. also check the seal on the tank. the backplates leack also, clean them up and put some RTV silcone on the backplate and lightly tighten it down