Nobody runs out of fuel purposefully. But we homesteaders do often tempt fate. Right? Luckily – the solution is simple if a modern diesel tractor with an electric diesel pump runs out of fuel. Fill the tank and start the engine.
But starting a diesel tractor with a mechanical fuel pump is different. You’ll have to fill the tank and bleed the fuel line.
Bleeding a diesel tractor fuel line can be intimidating for the uninitiated, but with these guidelines, your old tractor will be back in service – with no sweat.
- How to Start a Diesel Tractor That’s Run Out of Fuel
- How Do You Bleed a Diesel Tractor Fuel System?
- Conclusion – All Bled Out
How to Start a Diesel Tractor That’s Run Out of Fuel
When a diesel tractor with a mechanical fuel pump runs out of fuel, the best way to restart the engine is to bleed the fuel lines. Fill the tank with diesel and loosen the fuel filter and pump bleed screws. Then prime the fuel lines to remove air bubbles. Tighten the bleed screws and crank the engine until it starts.
The video below shows you some of the vital steps to take to bleed your diesel tractor. Find the full instructions below. And if you have any questions, please leave a comment! Dan is more than happy to help out.
Fuel lines on diesel tractors differ in the following ways.
- Older tractors have a mechanical injector pump. And often, a mechanical lift pump draws or pushes fuel from the diesel tank, through the filters, and into the injector pump that supplies the engine with high-pressure (atomized) diesel.
- Modern tractors typically have an electronic lift pump supplying an electronic injector pump.
- Diesel tractors may have more than one fuel filter.
To successfully bleed a diesel tractor fuel line, ensure the tank is filled to a level higher than the primary fuel filter to allow gravity to create the necessary downward pressure to push fuel through the filter to the lift pump.
- Follow a sequential process of bleeding the fuel filters, priming the lift pump manually, and cracking the injectors to purge the fuel lines of airlocks.
- Crank the engine to build the necessary pressure to bleed the injector lines.
- Tighten all bleed screws/nuts/plugs and injector lines to prevent fuel and air leaks.
What Happens When You Run a Diesel Tractor Out of Fuel?
When a diesel tractor fuel tank goes dry while the engine runs or during the starting procedure, the air gets sucked into the fuel lines. The sucking air creates an airlock, which deprives the fuel pump of hydraulic pressure, rendering it incapable of pumping fuel to the engine.
- Large diesel tractors have long fuel lines leading from the diesel tank to the high-pressure injector pump. The long fuel lines make bleeding a lengthy process.
- Smaller diesel tractors have shorter fuel lines and are easier to bleed.
Remember: Running your tractor till the tank runs dry can damage the engine. Why? Diesel supplies the necessary fuel for combustion. And diesel is also a lubricant for the injector pump, diesel injectors, and engine components.
How Do You Start a Kubota Diesel Tractor After Running Out of Fuel?
A Kubota diesel tractor that has run out of fuel and stopped will require bleeding the fuel lines between the diesel tank and pump.
- Typically, small Japanese diesel tractors like Kubota and Yanmar don’t need bleeding at the injectors, just at the fuel pump.
- Does the tractor have an electric fuel pump? Then you won’t need to bleed the lines. Instead, fill the tank with fuel, start the engine, and the electric fuel pump will supply the fuel lines with diesel.
How Do You Bleed a Diesel Tractor Fuel System?
To bleed a diesel tractor fuel system, follow a sequential process of removing airlocks from the fuel lines using pressurized diesel from the refilled diesel tank.
The necessary pressure to remove airlocks will be obtained by manually priming the lift pump for low-pressure lines (before the injector pump) and by cranking the engine (for high-pressure lines from the injector pump to the injectors).
Bleeding a Diesel Tractor Fuel System – Step by Step
- Fill the diesel tank with fuel higher than the primary fuel filter.
- Bleed (aka prime) the fuel filters (primary and secondary). Open the bleed screws one by one on the filters and follow the line to the hand primer at the lift pump.
- Use the lift-pump hand primer lever to pump fuel through the lines with one bleed screw at a time opened slightly.
- Pump until fuel flows out of the filter bleed hole – and until no bubbles are visible.
- Close the bleed screw.
Bleeding the Lines to the Injector Pump
- Remove the bleed plug from the injector pump and pump fuel through the lines with the hand primer until a strong fuel stream flows from the bleed hole and no air bubbles are visible.
- Put the pump bleed plug back in the bleed hole.
Bleeding the High-Pressure Injector Lines
- Crack the injector nuts by half a turn, one at a time.
- Put the fuel stop in (in older tractors).
- Crank the engine until a strong fuel jet exits each injector line (one at a time).
- Work through each injector line one at a time, purging all air bubbles.
- Tighten each injector nut tightly after bleeding.
Warning: Diesel exiting the injector lines during bleeding has insanely high pressure (+15,000 PSI, pounds per square inch). Whoever is bleeding the lines should stand well away from the tractor when the engine gets cranked to bleed the injector lines.
How to Prime a Fuel Pump On a Diesel Tractor?
Priming a diesel fuel pump requires removing all air trapped in the fuel line, from the diesel tank to the injectors.
- Loosen the bleeder screws (on fuel filters and diesel pumps), and pump fuel through the lines using a hand primer or by cranking the engine.
How Do You Bleed Air Out of a Diesel System?
You bleed air from a diesel system by priming each filter and pump in the fuel line.
- Loosen bleed screws on the fuel filters and injector pump.
- Pump diesel through the lines using a hand primer pump or by cranking the engine.
- With its bleed screw open, each component will get primed – purged of air trapped in the diesel system.
Diesel from the fuel tank is pumped through the fuel lines by:
- A primer or lift pump, operated manually or mechanically, for low-pressure fuel delivery to the injector pump.
- The tractor crankshaft (cranking the engine) powers the injector pump, producing (the necessary) high pressure for the injector lines.
Diesel engines are more reliable and longer lasting than gasoline engines. But that doesn't mean they're easy to repair! That's why we love this all-in-one diesel engine repair and troubleshooting guide from Paul Dempsey. The book contains hundreds of schematics, photographs, and drawings. It leaves out the guesswork - and can dramatically improve the diesel engine aptitude of any willing reader.
How Do You Bleed a Fuel System on a Kubota Tractor?
To bleed a Kubota Tractor fuel system, fill the tank with diesel, bleed the fuel filters using the primer pump, and crank the engine until the engine starts.
Smaller tractors generally only require bleeding up to the injector pump. In other words – there is no need to crack the injectors.
How Do You Start a Diesel Engine After Replacing a Fuel Filter?
After replacing a fuel filter on a diesel tractor, open the bleed screw on the filter housing and allow the fuel to flow out for a few seconds. Then retighten the bleed screw.
- Use the primer lever on the lift pump to create the necessary pressure to draw fuel through the lines.
How Does a Diesel Primer Pump Work?
Diesel primer pumps can either have a diaphragm or a piston and plunger to build pressure in the fuel lines. Diesel primer pumps can be operated manually or by cranking the engine.
- Diesel primer pumps are perfect when bleeding the fuel lines on diesel tractors with mechanical lift pumps.
- Hand primers are a manual way to pump fuel through the fuel lines and purge air from the system.
- Fitting an electric fuel pump will solve most fuel line issues.
- Bad Spark Plug Symptoms and How to Tell If a Spark Plug Is Bad!
- What If Lawn Mower Starts, Then Dies? Why Won’t My Lawn Mower Stay Running?
- Too Much Oil In Lawn Mower? Read Our Easy Fix It Guide!
- 17 Creative Lawn Mower Storage Ideas [to DIY or Buy]
- Greenworks vs. EGO Lawn Mower Showdown! What’s the Better Buy?
What Is Airlock In a Diesel Engine?
Airlocks are trapped air pockets in the lines between the various components of the diesel system, including the fuel tank, the primer pump, the injector pump, and the injector lines.
- A cracked fuel line will suck in the air and must get replaced.
Tip: By installing an electric lift pump near the diesel tank and bypassing the mechanical lift pump, you will eliminate the need to bleed the fuel system in your tractor!
Can You Flood a Diesel Engine?
A flooded diesel engine is an uncommon occurrence and is usually a result of a severely blocked air intake filter.
Conclusion – All Bled Out
If the diesel gods run out on you and your tractor runs dry, don’t panic! You now have the dope on resuscitating your workhorse with minimal sweat. If you own an old tractor, invest in an electric lift pump for a no-bleed machine. Or keep a beady eye on those tank levels!
How to Start a Diesel Tractor That Ran Out of Fuel – References, Field Guides, and Works Cited:
- How to Bleed a Fuel System
- Dealing With Massey Fergusson Bleeds
- Error Code Guy – Best Way to Bleed Diesel Engines
- Crankcase Vent Discussion – How to Find the Crankcase Vent
- Fundamentals of Medium to Heavy Diesel Fuel Engines
- What’s The Difference Between the Fuel Pump and the Lift Pump?
- Injection Pump Wikipedia Entry
- Bleeding Air From Diesel Fuel Lines and Filters