1987 ford f250 6.9 idi won't crank over?

On chilly morning truck started fine. Drove about 3 minutes shut it off. Then few minutes later it won't start no cranking or clicking. When attempting to start there's light water in fuel. Any ideas? Don't know anything about diesels

Well if it won't crank I'd start with cleaning the battery terminals, both batteries. The water in fuel light would normally mean there's water that has settled in the bottom of the fuel filter housing but in your case it might be a false alarm.

Bad cable connections somewhere probably. Check and clean battery terminals and cable ends, and make sure connection is tight at starter. Does the water in fuel light stay on when its running, or just when you turn the key?