Problem with Honda GX160 Kartmotor

Hi I have a problem with one of my Honda GX160 Kartmotoren. The engine runs out with undrawn choke when giving gas. Also several cleaning of the carburetor and all filters did not work. If you hold the suction nozzle with your fingers something it runs perfectly. Also with pulled choke it works. My guess He gets no fuel He sucks somewhere false air (rather improbable) Maybe someone can help me. MfG