Sealed engine , muffler, and carb fittings with red rtv. No leaks! Ran full tank through and no feul on engine at all.

The tank is a 3 line , all new lines and all tight, pressure check ok.

third line is fill line with a screw in it . Bottom line is from clunk to carb, and clunk is on bottom in corner of tank. Left line goes from muffler to a 2 inch alluminum tube through the gromet into the tank . Same for right line to fill tank. There is no feul tubing from the right and left fittings going into the tank just the 1.5 inches of aluminum tube.

No airbubbles till i hit 3/4 to full throttle. Its got me baffled, high rpm smooth even moving nose of plane up and down at 45 dgree angles.