Your lawn tractor may not be getting sufficient fuel to the engine for it to start and run. The good news for you is there are only a handful of items to check on your tractor to determine where your fuel leak is coming from. Most owners will be able to perform diagnostics and repairs on their equipment.
A lawn tractor may not be getting fuel because old fuel has caused deposits to develop in the fuel system causing restrictions in the fuel lines, fuel filter, and carburetor. A bad fuel pump or faulty fuel cap can also result in your lawn tractor not getting gas or diesel.
Refer to the owner’s manual for safety precautions to take before working on your equipment.
Reasons Your Lawn Tractor Isn’t Getting Fuel
Bad or Old Fuel
Over time, fuel can break down and cause problems to develop in a gas or diesel lawn tractor.
Gasoline-Powered Lawn Tractor
Most gas sold at fuel stations today contains ethanol. Ethanol is a corn-based fuel added to gasoline to make it more environmentally friendly than gasoline by itself.
While ethanol is safe to use in most vehicles, it is not good for the small engine used in a lawn tractor.
Types of gasoline that contain ethanol can begin to break down as quickly as 30 days after purchase. Ethanol and the moisture it attracts will separate over time and sink to the bottom of the fuel tank. This solution burns hotter than gasoline causing potential engine damage.
In addition to this, the solution can leave behind gummy deposits clogging the fuel system. These deposits can restrict fuel from getting to the engine.
I recommend adding a fuel stabilizer to gasoline you are unable to use within 30 days after purchase. A product like Sea Foam Motor Treatment will stabilize the fuel while reducing moisture and cleaning the fuel system.
For additional information on choosing the right gas and fuel additive, refer to these guides:
Diesel-Powered Lawn Tractor
Diesel fuel that sits for long periods forms solids and condensation in the fuel system that causes clogging and degradation.
Old diesel will have a dark appearance and your fuel filter will appear dark as it filters out the solids. A dark fuel filter is a sign your fuel is old and should be replaced with fresh fuel.
Note: Solids can begin forming in the diesel tanks at the fuel station. Always buy fuel from a busy fuel station.
Repair: Remove old fuel from the fuel tank using a fuel siphon and place it in an approved fuel container for recycling. Refill your fuel tank with fresh fuel adding a fuel additive to stabilize and clean your fuel system.
Plugged Fuel Filter
A fuel filter is used to filter fuel coming out of the tank to remove dirt and other foreign materials. Dirt and sediment can clog the fuel filter when it isn’t being replaced to ensure your fuel filter is in good condition and working correctly.
Repair: Replace a clogged fuel filter with a new filter so fuel will continue to flow. When installing, make sure the arrow on the side of the new fuel filter is pointed in the direction of the fuel flow.
The arrow should be pointed away from your fuel tank and toward the carburetor. Installing the filter incorrectly can result in a fuel flow problem.
Clogged Fuel Lines
Old fuel sitting in your lawn tractor can cause clogging of the fuel lines restricting fuel flow.
To find a clog in a section of the hose, use the fuel shut-off valve located at the bottom of your fuel tank to start and stop fuel flow. You can also use fuel hose pinch pliers to crimp the line to stop fuel flow.
Identify a section of the fuel hose to check for a clog. Stop your fuel flow. Remove the end of the hose furthest from the fuel tank and place it in a container.
This container must be placed lower than the fuel tank because fuel cannot run uphill without the assistance of the fuel pump.
Start your fuel flow and watch the flow into the container. If you are not getting good fuel flow, shut off your fuel supply and remove the section of the fuel line from your lawn tractor.
Repair: To remove the clog, spray carburetor cleaner into the line. This is used to help loosen the clog. Follow with blowing compressed air into the line to remove the clog.
If you are unable to remove the clog in the line or you notice your fuel line is dry and cracked, you need to replace it with a new fuel line.
Bad Fuel Pump
Over time your fuel pump can fail. Fuel sitting in your fuel pump can degrade the components or it can wear from normal use. When it fails, the pump is no longer able to draw pressure to pump fuel to the carburetor. Your lawn tractor will not get the fuel required to start and run.
Before you begin testing your fuel pump, confirm you are getting fuel to the inlet port of the pump. You may have already confirmed this by checking fuel flow through your fuel lines.
If not, check to make sure fuel is able to flow through the line attached to your fuel pump’s inlet port before checking your fuel pump.
Repair: Replace a fuel pump that is unable to pump fuel to the carburetor. Test this by removing the fuel line from the carburetor and placing it in a container.
Start your engine and watch for a steady or pulsating flow of fuel from your fuel pump. If you don’t see this constant flow, your fuel pump is bad and must be replaced.
The function of the carburetor is to regulate the amount of fuel mixed with air to form combustion in the cylinder. When old fuel gums the carburetor, it can clog the carburetor jet and prevent fuel from getting to the cylinder.
Before you start tearing apart your carburetor to find the clog and clean it, take this quick step to determine if your carburetor is the problem. Remove the air filter from the housing and spray carburetor cleaner into the air intake.
Start your engine. If it starts and runs for a bit and then shuts down, your carburetor most likely needs to be cleaned or replaced.
Repair: I recommend tackling the job of cleaning the carburetor yourself if you are a little mechanical and don’t mind working with small parts. If that’s you, follow my step-by-step directions in this guide to clean your carburetor.
If you are not this person and choose not to clean your carburetor, you can either replace it or have your local lawn tractor repair shop clean it for you.
If you choose to replace it, have the engine model and spec number to ensure you purchase the right part. This is not to be confused with the mower model and serial number.
Bad Fuel Cap
A lawn tractor’s fuel cap is designed to allow air to pass through the cap. When the cap is plugged and unable to vent, the fuel tank forms a vacuum due to the lack of air. When it acts like a vacuum, it prevents fuel from leaving the fuel tank.
Repair: Run your lawn tractor for a while with and without the fuel cap in place to test whether the fuel cap is the problem. If your lawn tractor runs fine without the cap, but shuts off with the cap in place and runs for a while, chances are your fuel cap is plugged.
You can attempt to clean the cap to remove the clog. If this doesn’t work, it’s time to purchase a new fuel cap.
Still Having Problems with Your Lawn Tractor?
You can encounter many different types of problems with your tractor as it ages. I have put together a guide to help you quickly identify the causes and solutions for the type of problem you are encountering.
I cover common problems like a lawn tractor not starting, smoking, cutting unevenly, vibrating, dying after running, and more.
Check out my guide: Common Lawn Tractor Problems & Solutions.
If you encounter a problem you don’t feel comfortable troubleshooting or repairing, contact your local lawn tractor dealership or repair shop for assistance.