[bowtie72]

I am fighting the same problem with one of my trucks. My 72 402cid 400thm. It has a q-jet. It has been sitting for a few years. When I was getting it back on the road the fuel pump was leaking. I replaced the pump with a cheap Oriellys pump. Thats when my problem started. I have owned the truck for about 20 years. It has never done this before. I have rebuilt the carb and checked float settings etc no help. My son drove it to school and it done it to him. I could pour water over the carb and it would boil it off.
So I know the fuel is boiling in the carb and building pressure that the fuel pump wont push thru. I am going to change the fuel pump to a better quality pump, and I have a phanolic spacer to try if that doesn't work. I think it is the cheap pump not pushing thru the vapors in the carb. I will let you know what happens.