RE: Brison 3.2 Carb Help!! (Where is Ralph when you need him!)
Could be gunk that you can't see.
I called it the jet -- metering needle-- sorta the same thing. The metering needle stops the flow of fuel from the jet into the bowl.
Some metering needles that I've seen have a rubber ring sorta built into the tip. I've seen this get clogged with gunk and cause it to not seat. Also seen the seat in the jet get clogged up. That could be the case here. Sometimes when an engine sits for a long time, all the gas will evaporate out of the carb, but the oil is left behind and it gets hard or sludgy.
With fuel flowing out and flooding the engine, that tells me that the pump is not being stopped and it's just forcing fuel into the venturi. That metering needle/spring combo is what stops the pump from overcoming the engine. The pump will move a lot more fuel than the engine can actually use.
I'd rebuild it, as you said. If that don't fix it, just buy a new carb. You can get Walbro carbs pretty reasonable now. Even if it cost ya $40, it's worth it. The hassle isn't worth the $40 if you can't figure it out and make it run good. I had the same problem with a Poulan 54cc engine once. Left it sit around for a couple years and then it wouldn't run right. I rebuilt the carb and fought it for a couple months. Finally got mad and sold it to a guy in Florida. Told him it had carb problems and sold it to him cheap. He just bought a new carb for it. Sent me a video of the engine yanking his Midwest Extra around like a rag doll. Rubbin' it in!! Why didn't I do that? [:@]