I really have had more than my share of fuel delivery problems in many of my cars/trucks in the last few years. My '79 300 had a degenerative fuel supply problem. At first, on a cold start, it would start right up then die after a few seconds. I'd stab the throttle again, and give it another crank, start right up and run fine. My hot starts weren't so good either, so I thought the needle and seat were worn and the engine was flooding. So I pulled the TQ apart and found some junk in the float bowl, so I changed the N&S and the fuel filter, too. It seemed to help for a little while, then the condition started to worsen again. So now, I started to think that the float bowl was empty because the bowl was leaking. Finally, it just wouldn't start at all. I worked the throttle by hand, no fuel. I pulled the fuel line at the carb, cranked the engine for about 15 sec, and only got one anemic little spit of fuel. OK, must be the pump. It looked like the original pump(140K), so I put on a new one. I should have first pulled off the inlet hose and felt for vacuum at the inlet nipple while cranking, But my 18 YO son is usually busy, and I 'm too lazy to dig up the remote starter. I crank the engine, still no fuel! I remove the inlet hose, put my finger on the inlet nipple while cranking, I can feel pretty good vacuum. So now I drop the fuel tank, clean it out(a little debris), and install a new fuel filter sock, even though I can blow easily thru the old one. I reinstall the tank, with a new filler grommet, because the original was cracked and dry rotted. I refill the tank, auger out the lines with a speedo cable, and blow compressed air and solvent thru the lines. I finish connecting everything up, fill the tank, crank the engine, and still no fuel! WTH! OK it's pouring rain outside, and I've got to fix this thing today. I try blowing compressed air back thru the lines, and have my son listen at the tank for bubbles, to make sure the pickup is actually submerged in the tank. Wait, how come I hear air escaping in the front of the car? I have my son pump air into the hose from the supply line from the frame, while I feel around for air escaping. The hose is kinda dry rot cracked where it is clamped to the hard line on the frame! I change out the fuel line hose, reconnect it, crank the engine, VOILA, nice strong fuel squirting from the pump outlet.
You skip just one diagnostic step, overlook the obvious, and it'll bite you on the butt everytime.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Been there, done that, now I check for air leaks through cracked rubber or "pinholes" in the hardline right off. I cap-off one end and hit the line with some air pressure, any leaks are pretty easy to spot.
Many ""bad fuel pumps" are really just a 30 year old cracked rubber inlet hose!
DD