Sounds like you're dealing with plumbing that depends on siphon action. Not sure why it is plumbed that way. Are there no outlets in the bottom of the tank?

The stock fuel system is built around gravity feed. The tank outlet is higher then the fuel pump. The pumps only job is to lift fuel to the carb.

Your buddy is correct. Inline electric fuel pumps 'push' fuel. And they aren't good a dry starting a siphon. They expect gravity to deliver fuel - which they in turn push forward and up to the carb.