When a diesel tractor runs out of fuel, it requires a little more work than just filling up the tank before it will start again. Air that was introduced into the fuel lines must be removed before the tractor will start. To do that, the lines must be bled to allow the fuel to force the air out. Although the process varies slightly between models and types of engines, the general process is the same.
Fill the fuel tank. The added pressure of the fuel with help flush air out of the lines more quickly.
Find the bleeder screw nearest to the tank; refer to the owner's manual if you need to. It will be located at the top of the fuel filter valve. Loosen the bleeder screw a few turns with the adjustable wrench.
You will need to prime the fuel pump until diesel fuel comes out of the bleeder line without air bubbles. Most tractors have a hand primer next to the fuel pump to accomplish this. If your model doesn't, you will need to have your assistant crank the engine in order to prime the pump. Once diesel fuel comes out of the bleeder screw without any air, you may tighten it.
Loosen the nut on the delivery pipe to the first fuel injector line if it is a four-cylinder engine, or the nuts on the first two pipes if it is a six-cylinder engine. Continue to prime the pump until only diesel comes out of the injector lines. That removes any air from the injectors. Once all the air is out of the lines you have loosened, tighten them again.
Continue the process of loosening the injector lines one by one and priming the pump until the air has been removed from all of them.
Turn the key and continue cranking the engine until the tractor starts. Allow it to run for at least 15 minutes before shutting it off. That will give you time to ensure that all the screws you have loosened are tightened properly.