Have a look at the in-tank fuel filter, on the end of the pickup hose - see if you can suck air through it easily. Apart from accumulated dirt, it is commonplace to get some water in the tank - just a small amount of water can stop fuel going through that filter, while leaving it still looking clean. Check also for splits in the pickup hose, and loose screws or damaged gasket at the carburetor insulator. Those are the most likely causes other than a fault in the carburetor.
