When you remove your gas cap is there an in-rush of air in like a vacuum? Is there an out-rush of air like the tank is under pressure?
What's the story on the fuel tank? Is it new? Is it original? You may have some debris or piece of some crap in there that's plugging the line as it exits the tank. Maybe adding fuel moves it into position or something.
Is there a fuel filter anywhere?
Regarding the pump; If you ever need to replace the fuel pump, under no circumstances purchase a new pump off the shelf from anywhere. They are all absolute junk from China and will not work. Purchase a rebuild kit for your original pump from Then and Now Automotive or send yours to them for proper rebuilding.
