How do I prime my fuel system?

if you're careful you can do what I do: I use a an air nozzle, wrap a rag around it, stick it in the filler neck, GENTLY pressurize the tank. this will push fuel to the front, fill the carb and even give a pound or two of pressure in the entire line. That will help check for leaks between the tank and pump.

Obviously, this would not be a good time to do something unfortunate like blow up the tank or something. You can start with a couple small tests, you can feel the air pressure coming out as you pull the rag/air nozzle away, get an idea where you're at.

if there's a vent it'll need to be pinched off. I have some small needle-nose Vise-Grips that work well for this.

Yes, it'll push right through the pump. the pump is just two sets of check valves.