Voltages all look good
Does the Fuel Pump relay Click on when key is turned on?
It should click on for 2 seconds then click OFF
If not the you need to find the VIP(OBD1) connector.
It is in the engine bay and "usually" near firewall in corner on drivers side but also passenger side, follow main engine wiring harness.
In your above diagram you see VIP test connector, center right, spliced to the Light Blue/orange stripe wire
In your picture it looks like it might be right there next to relay base
Image here shows you what to look for: Ford Ranger - Testing EEC-IV Equipped Engines
Second drawing down
It may have a cover that has EEC on it
Fuel Pump slot on the VIP connector is labelled in the drawing.
That Slot is the GROUND for the fuel pump relay, computer grounds(pin 22) this wire to turn ON the fuel pump, close the relay.
So with key on use a jumper wire in that Slot to a Ground, engine, fender bolt, battery "-" any ground will do.
You should hear the "click" of fuel pump relay closing and fuel pump should start running.
You can leave this connected and start the engine, won't hurt anything, you are doing the same thing computer should be doing.
If you don't get the "click" then the Ground wire at the relay is bad, assuming your test voltages were accurate.
If you do get the "click" then computer is not Grounding pin22 wire or wire from pin 22 to fuel pump relay is bad.
computers rarely fail, so 99.99% a wire issue
You can drive the truck using the jumper wire in place, fuel pump will go off when key is off.
But it is a safety issue, computer cuts the Ground to relay if engine stalls(RPMs below 400), i.e. broken fuel line in an accident, which prevents a fire, inertia switch should as well, so just a heads up on that.