A hot fuel pump won't be a problem.
Originally you said you saw a wisp of vapour coming out by the choke plate. That indicates a high float due to something stuck in the needle/seat or possibly too much fuel pressure. After you warm up the motor leave it running and look into the carb below the choke plate. You might see a little raw fuel in there. And you might hear a slight crackle inside too. It doesn't take much flow to cause it to flood.
You might need to pull it apart to check the float and needle/seat.
First try the look see in while running (use a small flashlight to see better). If you see fuel then tap near the inlet with the end of a big screwdriver. Sometimes that will dislodge any junk in the needle/seat.
Or while running pinch off your fuel hose with some pliers, hold it about 10 seconds then let it go. That might flush it out.
Here's a link to a quad rebuild with pics. The carb there is similiar to yours except for the other pull off pot on the front.