Yeah,
Exactly what Ed said. Get the fuel tank where it belongs. This seems to be a lost piece of knowledge these days with all the ARFS around. But even ARF airplanes have some big mistakes. On the inverted setup the tank centerline should be slightly below the center of the carb on the FL-70 (where the fuel dumps into the venturi not the location of the Needle Valve as many engines now have remote needles).

Inverted 4 strokes are normally the easiest way to go. They start better that way and don't flood as easily. The valves allow excess fuel to be dumped each revolution. Just get your tank in the right location and quit fooling around with expensive fixes!

Jimnie