Have an inverted .75 Tower engine on a UCANDO. Set needle to 4.5 turns out for first start...per factory instruction. Has cowling, and external fuel dock, and I have the Needle valve at a remote location (though I did try it at factory location). Both lines are hooked up correctly. Tank fills just fine. The problem is that in order to keep the engine running, I have to pinch/ restrict the exhaust port in order to produce enough back pressure to pressurize the fuel tank and get the fuel flowing to the carbeurator. The tank is preset to the correct height and appears ok relative to the carb inlet. The minute I take my hand off the exhaust, the engine sputters and dies. My thought is that there is an air leak... also checked the tank and the fuel and vent lines are in the correct orientation.....just not generating the pressure.

Anyone have any suggestions?