I have seen some crazy things with engines. Do it in steps. You have already started with the tank, not it. Moved on to the lines, not it. fuel nipple next. Take your high end needle out open the card and see if any fuel runs out. Something as small as a grain of sand can cause your problem in the carb. I have also seen this with a GWS 47 I had. In the end it was cylinder sleave that had moveing. I also had the same problem with a SuperTigre 2300 I mod the carb on. It was trash in the high needle. Good luck!

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