Jorge, Happy Memorial Day weekend!
You have likely already done this but I would start by connecting a portable fuel tank to your fuel water separator and seeing if that works as normal. Assuming the valves on the fuel/water separator are open, that would eliminate the fuel pump and anything else from the fuel/water separator to the motor.
That leaves:
1). Valve at fuel/water separator is closed (hey, its easy to do, but fortunately as easy to fix)
2). A clog in your fuel pick-up tube or elbow (I've experienced this)
you maybe able to disconnect hose and blow into it. If it bubbles the fuel like a water pipe, the flow is good. However something may be getting sucked into the tube.
3). A broken or separated fuel pick-up tube (Gonna have to go in)...
4). A clog in in your vent (should be able to hear or feel air as you fill tank)
5). You are simply out of gas
(I've experienced this thinking I had plenty of fuel)
Good luck. Keep us posted.