I had that problem too but found that most of the fuel ran accross the butter fly valve and out the side of the carb. But the unit was quite old and the hole for that butterfly shaft was worn. I took the butterfly out and shaft out, cleaned up the hole and used some JB weld to put on the body where the shaft goes through. Put some oil on the shaft as a releasing compound and reassembled. When fairly hard i worked the butterfly. Also polished the shaft and hole some, later on. It has good close tolerance now and the fuel. stays inside the engine anyway.
