The relationship of the fuel tank to the carb is very important. The horizontal centerline of the tank should be no higher than around 3/8" above the needlevalve (spraybar). However priming the way you are should flood the carb. Check to make sure you have not inadvertantly switched the pressure line with the feedline, i.e. the feedline is the one from the carb is the one that goes to the clunk in the tank. An easy mistake that happens all the time.

John