There are only so many things that could cause this. The tank being contaminated and restriction fuel flow, a bad fuel pump, something in the carb.
This may not be the issue, but has the tank been cleaned? Is there any possibility that something could be floating around in there, getting sucked onto the fuel outlet and stopping the flow?
What is the condition of the fuel pump? You have a gravity flow from the tank to the pump and then the pump works to suck and push the fuel to the carb. The fuel in the bowl may just be flowing in from the tank.
Only asking to eliminate things.
Probably a heat issue, but a little out of my knowledge area.
Was the fuel bubbling because it was hot or was it because of air being forced into the bowl?
It is a Rochester and as talked about in another thread, they are very problematic in my opinion.
