You have gotten some solid advice in the responses prior to me jumping in. I thought I would share the fuel pump test specs for pressure and volume. For you to lose fuel delivery so quickly is an indication you have a fuel pump issue as opposed to a fuel flow blockage issue (filter). Any time I hear about a failing or failed fuel pump I recommend immediately to pull your engine dip stick and see if it has an odor of gasoline. The reason is when a rubber diaphragm inside a fuel pump fails the fuel is often pumped into the crankcase, which will seriously destroy the oil's ability to properly protect your internal parts. In fact, I would do that before performing a fuel pressure pressure ot volume output test, just because it is so critical. Even if you "only think" you smell gasoline, I would not take chances, Engines are very costly to replace or rebuild - especially when it is avoidable.
As for the specs and some photos, I have attached a few files I hope you find useful. The fuel pump performance specs are near the end of the PDF file.
While you are working on the fuel pump (if the fuel pump needs to be replaced) I suggest you change the rubber fuel lines at the fuel tank fuel outlet, at the fuel pump fuel inlet, and at the fuel filter. The filter's fuel line has likely been changed a few times, but the others are normally changed only when they begin to leak. Even my own 50+ year old pony cars came to me with their original fuel lines at the tank and at the fuel pump.
If you have never changed a fuel pump before, it is fairly easy. The trick is to block fuel from pouring over you, coming from the fuel line from the fuel tank. Obviously prevent fuel from getting in any eye, or worse yet inside an ear as it is very painful. In looking at the photos of hoe the fuel pump actuating arm rubs against the camshaft eccentric, you should be able to see how craanking the engine a little at a time so the actuating arm is rubbing on the low spot of the eccentric. That will relieve much of the ac tuating arm spring pressure you will be dealing with when trying to assemble the fuel pump and getting it bolted into place.
I have a few YouTube videos showing how to replace a fuel pump, and fuel lines, on a 73 Mustang with a 302 engine. If you have a 351C the biggest difference is where the mounting holes are located. Other than that it is really the same process. That videos are at:
https://youtu.be/frYaO_u0OZc
https://youtu.be/Xp8vLVlxtVk
https://youtu.be/BmQpNEHPgaw
https://youtu.be/lkKVcliOd2w
If the fuel pump tests good please let me/us know so I/we cqan begin to suggest other approqaches. Likewise, if the fuel pump tests bad, and you get it installed and the engine running (with oil and filter change), please let us know that also.
Ciao!
Gil
