hotrod wrote on 02/06/20 at 20:49:39:Could be the gas cap. The vent may be stopped up.Try just a few quarts in the tank with the cap removed, as so to not make a mess. If it runs fine, then it's the cap. I had that problem and it was the last thing that I checked. It drove me nuts for a while. The vent in the cap is very small.
Seems like a quick test would be simple.
Fill up
Go home
Pull the fuel line off the carb
Poke it in a gas can
Put it on prime
If it doesn't drain with a steady flow, ,,,,