Sometimes when a fuel tank is just filled, the engine-tank pressurizing couldnt work at beginning until some fuel spending to make enough pressure established.Try this: After starting engine give half throttle and quickly plug and release the exhaust outlet with finger but not to stop the engine, sure..This will make enough fuel come to carb.After 2 or three such attempts try to give full throttle.If you can,its better to try this at full throttle without stopping engine.I had to do this several times on 2 TT42 GP.