Just Bought an 85 F250 -- Have Questions

[echo412]

Hey guys I just picked a 1985 F250 6.9 diesel. The truck has an issue where it dies after few minutes. The previous owner has changed below items to no avail:

"NEW AIR CLEANER, ALTENATOR, STARTER, FUEL PUMP, BATTERIES, FUEL FILTER, BRAKE LINES, NEW TIRES AND NEW WHEELS IN BACK, BED LINER, OIL AND FILTER JUST CHANGED! COMPLETE UNDERBODY AND SUSPENSION HAS BEEN SPRAYED WITH BLACK UNDERCOATING. "

What do you guys think the problem might be? What are the first things that I should look into? Thanks guys

BTW I knew of this issue before I bought the truck.

[CDX825]

Sounds like air entering the fuel system on the suction side of the lift pump (fuel pump on the side of the block) to me. Take the filter off after it stops running and see if its full of fuel. Probably wont be.

What the fuel level in the tank your running off of? The pickup tubes were known to crack and cause issues below 1/3 tank.

Could also be the water separator on the drivers side firewall letting air in through the drain. If fuel is dripping out of the drain tube an easy fix is to stick a bolt in the tube to block it off.