Fuel Vaporization Using Eddy Carb -- In-Line Fuel Pump Question

Yes, I have a fuel solenoid on my Ford 8N tractor. Since the fuel tank is on top of the engine, when cut off, the pressure from the fuel can unseat the needle in the carburetor and drain all the gas onto the ground. Since it's an updraft carburetor, it will not fill the engine. But I think that's unnecessary in your situation. You need to find the problem and fix it.

Have you tried another fuel pump? A stock replacement is cheap enough to try to confirm that fuel is not passing back through the pump from the carburetor. That sounds like what is happening. The fuel is not just vaporizing that quickly from the carburetor. No way that much fuel is evaporating. That's a lot of fuel in that float bowl.

How is your fuel filter positioned? If it is vertical, that can pose a problem, as the fuel will tend to run out of the filter easier. I have mine mounted horizontally, on the passenger's side of the carburetor, right above the intake.

Although mine does spin the engine a little when hot, I am nowhere near concerned that it spins enough to hurt the starter, so yours must be much worse. Mine might spin 5 seconds at the worst and that's all. That will never hurt a thing.