Thanks!
I also recently replaced Fuel Shutoff Solenoid because it was acting like a fuel issue. I came close to gutting the old FSS but replaced it instead. Will try clear fuel return line when I get time.
1996 K2500 suburban 6.5 TD. Replaced FSD and relocated behind front bumper with new FSD pigtail harness. Ran for 20 minutes and shut down tried to restart, lift pump running but no glow plug light. Waited 5 minutes, got glow plug flicker, it restarted and shut down again after a few minutes...