Ken,
The first thing, I'm not an expert, but I would want to take the fuel line loose at the first fuel filter and see what kind of flow there is when it quits running before moving it. There may be down by the frame a fuel strainer or it could be back by the bottom of the tank. Also if it has a shut-off valve at the tank, this is a good place to collect trash. I have seen a rock in a backhoe fuel tank that after time was completely ground round and would close off the fuel line. Of course this was on flat ground. If this has a lift pump some of those also had a screen on them. Now to the pump-if it is an IHC I would imagine it has a rosa-master CD pump. Some had a screen on the inlet line and there is also a check valve on the low end side or return line that will cause the engine to choke and die if it is sticking. If you have good flow to your filters this check valve would be the next thing I would want to check. Take it off and see how it runs. Yes, your electrical is being fed by the oil pressure switch. This makes it nice because it only turns on when it has oil pressure. I wouldn't be too quick to put a pump on it because it was designed to run without it. If you don't have a lift pump and the transfer pump is all in one they are still not that expensive. If you have to take it off, on the side of the pump will be a plate with two screws. Remove plate and rotate motor by hand until scribe lines line up, and if there is a pointer on front crank or back on the fly wheel this will have your pump in time on top dead center number 1 and ready for removal. Now you can take it to a diesel service and they can bench test it. I doubt you have to do this because it is probably in the line or there is a water separator you are not finding hidden down in the belly pan. If this doesn't help, send plane tickets! LOL
