no power to fuel pump on 1990 Ford F-150

just to day truck would not start fuel pump not getting power

4 answers
First check the fuse( i think it may be under the hood) then the relay. If these check out, there is an impact switch that cuts off the fuel pump in a roll over or high impact. It is in different locations,... frame, under floor mat, Etc.
fuel selector switch if duel tanks
So, if the inertia switch has no voltage, will the fuel tank selector switch have no voltage also? I have the ability too put a jumper wire @ fuel pump relay, under hood, from yellow to green, and, it kicks the pump inside the tank on. I have not got voltage at inertia switch, or either fuel pump while cranking. This is a 1994 F-150 4.9L 4x4 duel tank, both tanks have pumps inside. My relay is on drivers side in a big box with the fuse's. I did checks at the relay like this with my voltage meter; low current test from green to ground (yes power with key on); High current test from yellow (yes always
The inertia switch (incase you roll over) is under the dash and can go bad. You should be able to jump it out to see if that is the problem. I had close to the same problem my computer stopped sending a ground signal to the pump relay.