Fuel Pump Relay under the hood no power.

Did you roll your truck or something of the sort? Is this why you were asking about the inertia switch?

There are both a fuel feed line and a return line. Quick disconnects in front of the gas tank. Remove the feed line. Aim it into bucket or gas can. Have someone crank the engine while you watch. The fuel should come out fast with a decent pressure behind it.

If it isn't, then there is your issue.

 

Are they marked feed and return with arrows, colors, anything? I'm curious.

 

They are not. Look in the engine bay. The feed line attaches to the driver side of the fuel rail, near the firewall. Follow backwards from there.