How do you get a 2003 Duramax diesel to restart after it has run out of fuel?

If it has a fuel filter near the pump, remove it, and fill it up will fuel, and replace. You might want to check the owner's manual as it may have the other methods of restoring fuel pressure. Diesels are notorious for this, and some worse than others, just depending on the fuel system design.

Some have a bleeding valve close 2 the fuel filter-if so,open the valve & turn the key on for 5 seconds DON"T START IT ? IF that U may have 2 manually bleed the Injectors.