The system should have a vapor separation can. It should have 3 lines off if it. One to the carb. One to the fuel pump and one to the tank. At least the first generation had that. Or you can go electric and run an external bypass regulator that recirculates back to the tank. I used a Tee with an orifice to control pressure.

on the Jet valves. They were designed to swirl the mix as it comes in. But since they are small they will glow hot and cause backfires or they will burn and crack causing low vacuum. Or they will fall off and bang around inside. But the head will crack between the jut and intake.