How to bleed air from a diesel fuel system after running out of fuel

Running a diesel tractor out of fuel, or changing a fuel filter, can let air into the system and leave the engine cranking without firing. Diesel engines rely on solid fuel pressure, and even a small air pocket can stop them cold.

Start by refilling the tank and locating the bleed screws, typically on the fuel filter housing and the injection pump. Your operator's manual will show the exact locations and order, which matters.

Many tractors have a hand primer pump. Open the first bleed screw, pump until fuel flows without bubbles, then close it and move to the next point downstream. Work in order from the tank toward the injectors.

If the engine still will not start, cracking the injector lines slightly while cranking can purge the last of the air. Wear eye protection, keep clear of the spray and tighten everything once fuel flows steadily.