Did you try replacing the fuel filter yet? I'd get one from a Nissan dealership just in case it does have a anti drainback valve in it. A new fuel filter is never a waste of money.
Did you replace the gas cap? Mine
always has positive pressure on the gas tank. By positive pressure I mean that when I unscrew the cap, it hisses because of the pressure release.
Since doing the prime 3 times didn't help, you might want to ask the dealer if there is a anti drainback valve in the fuel tank or elsewhere along the line. The fact that priming it 3 times doesn't help tells me that either the line is totally draining back into the tank when it sits for 8+ hours or it could be dumping the fuel out of the line. You might also want to check to see if you have a leak someplace. It could be a really slow leak that won't show on the ground. Gasoline evaporates fairly fast. Look for a clean spot near the fuel line.
When you do find the problem, please post back.
Good luck!