91 F800 fuel delivery

[Problems]

My ford 7.8l F800 just started shutting off after 15-20 minutes of idling. About a week ago there was a puddle of fuel underneath the fuel/water seperator and thats when this whole issue started. I replaced it, primed it, and the truck started fine but once again it died. Even if I primed it again, it would just keep dieing after 15-20 minutes. I later noticed a little stream of fuel coming from one of the lines which I just replaced today, but its still dieing after 15-20 minutes. I took it for a drive today after replacing the line to see if it would die while driving, and it acted normal(as in no cutting out, or any problems)
When I first got the truck it never did this. It has a low idle at 500rpm, the original mechanical fuel pump, and no leaks from what I can see. All 3 of the fuel filters have been replaced.
Anyone have any ideas?

 

[Delmer]

I'd say the fuel water separator is a SMOKING GUN in this case. I'd bypass it for testing purposes, unless you can be sure you aren't getting a leak there. Are you sure all the filters had the correct gasket, and didn't have the old one stuck on still?

A picture of the fuel system and water separator might go a long way. I assume this is an inline Bosch pump? but the filter setup might be something unexpected.

 

[Problems]

Well there's the entire fuel system. I replaced all the fuel filters a couple months ago and the truck ran fine. As of right now. After I stop pumping the primer, I hear a high squeal coming from something(most likely a line) but I dont see and drops of fuel

 

[Delmer]

The transfer pump in the middle pic is notorious for leaking air, but I dont' think that would squeal when running, or cause it to stall while running.

If you have a squeal that you never noticed before, you could try brushing oil onto the water separator and lines on the suction side of the transfer pump to see if the squeal goes away, that will be your leak.

 

[thepumpguysc]

The squeal is just the overflow valve.. check to see if it’s coming from the fitting & line below & behind the double filter set-up on the inj. pump..
U should take it off the pump & see if the spring is broken from the back side.. & see if the adjustment is lose from the front side..(flat head screwdriver)

 

[funwithfuel]

Have you replaced all the rubber compression sleeves? They are notorious for sucking air.