Diesel tractors are usually much more reliable than gasoline tractors. They are known for their durability and the fact that you can store them for long periods of time without affecting their start-up mechanisms. That’s why it’s so frustrating when your diesel tractor keeps stalling.
Diesel engines need three things to run; fuel, air, and compression. If your engine is not getting one of these three things in proper amounts, it can sputter and stall.
The 7 common causes of a diesel tractor stalling include:
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- A fuel delivery issue
- Clogged or dirty filters
- Fuel contamination
- Blocked or damaged hoses
- Incorrect parts
- Broken fuel cap
- Fuel shut off solenoid malfunction
Let’s break down each of these points of failure and see if we can identify what’s causing the issue and get you back to work.
Make Sure The Fuel Cap Vent Is Not Clogged
The most common cause of a diesel tractor stalling is a clogged or damaged fuel cap vent.
Diesel fuel caps have vents to prevent a vacuum effect. If the vent is clogged, the engine won’t be able to properly pressurize, and the engine will be stifled and die (source).
To check if this is the cause of your problem, it’s often recommended that you remove the fuel cap, start the engine, then run it for an hour or so.
If the tractor runs without issue, then the problem is the fuel cap. Either try cleaning the cap, then putting it back, or order a new one.
But I don’t like that troubleshooting approach because you can introduce impurities into the tank if it isn’t capped. I generally recommend removing the cap and giving the vent a good cleaning then seeing if that solves the issue.
Determine if You Have a Fuel Delivery Issue
Another common reason for diesel tractors to stall is a fuel delivery issue. Assuming you have enough diesel fuel in the tank, check the engine hoses for blockages.
Then, check your fuel filter. Often, the fuel filter can get clogged on the intake side of the filter. One way to check this is to remove the fuel filter (bypassing it) and see if the tractor runs. If so, the filter will need to be replaced.
Examine Your Filters
Air, pressure, and fuel are the crucial components of a diesel engine. Filters affect all three of these mechanisms.
If the fuel filter is clogged, the fuel will not flow through it and cause the engine to lose power.
If the air filters are clogged, like in the fuel cap, the engine will not be able to pressurize, and again the tractor will stall.
There are other air filters in the engine, and surprisingly often these are installed backward. This causes the filter to block air intake instead of clearing it.
Another potential cause of a diesel tractor stalling is that your fuel has been contaminated (source).
Some of the most common types of contamination of diesel fuel are:
- Water. Water is very damaging to your diesel engine. If your diesel gets contaminated with water, it can cause the iron and steel components to rust. This rust can in turn clog your fuel filter.
- Inorganic debris. Particles of sand, dust, and rust may contaminate your diesel fuel. These can clog the filters in your engine, and prevent it from running properly.
- Organic debris. Even the smallest amount of water introduces to your diesel fuel will, over time, give life to microbial bacteria. Bacteria, molds, and fungi can grow in your stored diesel fuel.
Look for Blocked or Damaged Hoses
The hoses on your tractor are vital for the transferring of fuel from the fuel tank to the engine. To check these hoses, remove the fuel lines from the tractor engine, and hold them up to the light. You should be able to see any large obstructions.
There are two main lines to check:
- The line between the tank and the fuel filter.
- The line between the fuel filter to the injector pump.
If you’re sure that the hoses are clear, and punctured or cracked, you may still have an issue with your fuel lines.
The fuel is delivered to the engine under high pressure, if there is any amount of air in these lines, the engine won’t run. To fix this, the fuel lines must be bled to remove any air pockets from the tubes.
This YouTube video offers some practice, best practices for preventing fuel issues in a tractor:
Ensure Your Tractor Has All of the Correct Parts
It is a surprisingly common issue; your tractor won’t start because somewhere in the machine, the wrong part is in place. For instance, your fuel cap may actually be a gas cap and doesn’t have the proper vents to pressurize the engine. You may have the wrong sized filters or hoses for your engine.
Perhaps one of the parts is installed incorrectly, like the air filter being installed backwards. Or perhaps your mechanic over tightened a screw while installing a part, and stripped the thread, causing the piece to loosen over time.
Examine the parts of the tractor that you know, and ensure that they are the correct ones and properly installed.
Electric Fuel Shut Off Solenoid Malfunction
Another potential issue that you are facing with your diesel tractor is a failed part, such as the fuel shut off solenoid. This part is required to open and close to direct the flow of fuel to the engine.
The solenoid may malfunction and become stuck in the closed position. This won’t allow fuel to get to the engine, causing stalling. To fix this, you will have to replace the solenoid altogether.
While the solenoid is one potential part that can malfunction, it’s true that your issue with your diesel engine could be a broken mechanical part. You may have encountered a blown gasket, cracked seals, or seized engine parts.
These are often best dealt with by a professional.
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When to Call a Professional
Speaking of professionals, it’s important to know when to call one. The best rule of thumb is “when in doubt, send it out”. If you are at all unsure about your skills as an at-home mechanic or are worried you will damage the machine further, sending your diesel tractor to a professional mechanic shop is the best choice to fix it.
In summary, if your diesel tractor keeps stalling, there are a few main issues that could be causing it.
The most common of these is that your fuel tank cap is clogged or damaged. To test this is simple: try running the engine for a while with the cap off. If the engine works without stalling, simply replace the cap and move on!