I have searched other post on the subject but can’t find the exact same problem I have, so here goes. 87 6.9 crew cab Dulley diesel. (Hope this first part isn’t a red herring)So I recently Had the transmission rebuilt, so the truck sat for a bit. Maybe a month (had to take it out twice due to leaking fluid after the first time I reinstalled it) Got it all put back together and started it up and she ran great. Drove the old girl probably 5 miles and she stalled. After Some time of trying to find out why I turned to the fuel. Pushed in on the Schrader valve, nothing but air. This went on for a while. Finally after 10 min. of fiddling with it I got fuel to come up. When I got it running again I limped home, ran rough but just pulled in the driveway and died again (less then a mile) This time I went right back to the schrader valve and nothing but air. Not even a little fuel. After a short time got fuel to come out again and she started and Sat at idol for an hour or so and sounded great. Pulled her out of the driveway and didn’t even make the corner and stalled. This time as soon as I got her started I stayed at the schrader valve. Even though I had just got fuel to come out of it, while it was running pressed the valve and air, no fuel. And within seconds the truck began to stall. Got on the peddle so she wouldn’t stall she started to sound good again, so back to the valve pressed, air, started to stall. Rinse and repeat. I’m kind of lost from there. Things you should know. Did a return line kit last year following this forums advice. Also no mechanical pump, went to a electric pump a few years ago, also following directions from this forum. I think my next step is going to be to replace the fuel lines all around the engine compartment with clear lines so I can see the air coming up. I’m guessing it’s has to be in the lines before the schrader valve. And of course I have not seen an obvious fuel leaks where air might get in.
Sorry about the book. Thanks in advance for any advice you may be able to give on this subject

 

where did you mount the electric pump?

my first thought would be unhook the discharge hose from the electric pump and turn on the ignition to make sure the pump is putting out a consistent stream, if it was inconsistent then I'd start moving backwards,

If you had a consistent stream I think I'd bypass the fuel filter and hook up the electric pump directly to the IP to help confirm if the leak is in the fuel filter system,

best way is to hook up a Gerry can/pump to the bumper to eliminate everything from the IP back,

 

what type fuel pump did you put in?
if it was a generic auto parts store type pump, my bet is a bad electric pump.
if pump is good, second guess would be broken pickup in fuel tank sucking air .this is a common occurrence in these trucks, and usually happens around the 1/4 tank mark.

 

after you test the electric pump check to see how much fuel is in the tanks.... you may have a fuel pick up issue if the pump is working right.

EDIT: it could also be the Fuel tank select Valve