Ford Ranger Fuel Pump Problems

Have a '92 Ford Ranger, standard cab, 4cyl manual trans....
This one has me stumped. I've talked with mechanics, I've gone through the repair manuals....and I'm lost on this one. Started out with ignition problems. Got that fixed by replacing the crankshaft sensor. Right after that
it stopped running again. At first we believed it to be ignition related, but after investigating further, we found the relay to be bad..or so we thought.
Replaced the relay, the truck started a couple of times, and we were back to
square one. We couldn't hear the pump come on, so believing we had a bad
fuel pump, that was replaced along with the fuel filter.
Now...it's hit or miss....it might start and run 5 minutes or an hour...then it
quits. When we turn the ignition key, we can hear the relay click in, and there's about a 50/50 chance you'll hear the pump come on. Even then, the pump may continue to run.....and then it may not. I'm lost on this one..
Anyone have any ideas?

maybe a loose wire or bad ground but good luck locating it. Does it start right back up after it dies or is it dead for awhile. also could it be related to the ignition switch itself.

sometimes it starts right back......and sometimes takes a while. Don't think it's ignition switch related since the pump relay under the hood activates each time the switch is turned on. Loose wire....short....yeah...that could be a real problem tracing.....

THANKS!!