F-150 Ford have to prime gas to start

I have a 1994 ford f-150 truck 300 6cyl 4.9L fuel injected, twin tanks. Yesterday while driving it just shut off, I thought it might be one of the two fuel pumps, I hot wired them and they are fine, then I thought It might be the fuel relay, bought a new one installed it and truck still won’t start, Because I found the relay has 12 volts going into it but only 6 volts comming out, the pumps need 12 volts to work, do you know whats wrong?

I am a first responder with a VFD in Pontiac Mo. We have a 1987 Econoline 350 van that was originally an Ambulance conversion. The problem that I have is that when warming it up about 2 weeks ago it started fine and quit after approx. 1 minute of running. It quit abruptly, no hesitation like when running out of fuel while driving. There are 2 gas tanks but the rear tank leaked and therefore it has not been used for a few years. I was told that there are 2 fuel pumps for this model one in the tank and another I found on the under carriage. AC Delco (EP 90) is part number on this one. I am trying to avoid having to drop the tank. I wired the part described directly to a 12 volt battery and got no response (no buzz, vibrate, hiss or anything). The vehicle will start as we performed a test using the starter fluid and then a small amount of fuel directly to the carb. Therefore, I determined the problem was fuel delivery. Are there other checks I could make to be sure this is the problem? I also cranked the engine after disconnecting the part above and left the line from the tank open but no fuel was coming from it during that procedure. The VIN is 1FDJS34LOHHB45682. Someone mentioned that this vehicle may have Throttle body fuel injection but I do not have knowledge of such on any fords. Looking for pumps under parts I get several and many different types. Any assistance you can give is appreciated