A sign your Kubota lawn mower isn’t getting fuel is when the engine begins to run sluggish, quits or won’t start. Luckily, if you know your problem is definitely in the fuel system, there aren’t too many components to troubleshoot to find the root of your fuel issue.
A Kubota lawn mower isn’t getting gas when old fuel in the mower is causing fuel restrictions; dirt and sediment is plugging the fuel filter; fuel lines are clogged or kinked; the fuel pump is bad; the carburetor is dirty; or the fuel cap is not venting.
Follow the safety precautions listed in your Kubota owner’s manual to prevent injury before you begin working on your lawn mower.
Reasons Your Kubota Lawn Mower Isn’t Getting Fuel
6 Bad Fuel in Your Kubota Lawn Mower
Ethanol found in gasolines today will naturally attract moisture from the air. Over time, this ethanol and water mixture will leave gummy deposits in the fuel system causing blockages in the fuel system. This solution can also cause corrosion and premature failure of the fuel components. These fuel restrictions and failed fuel parts will prevent your mower from getting the fuel it needs to run.
Read more about the right gas to use in your Kubota lawn mower here. I further explain the effects of ethanol in your fuel in addition to helpful tips to store and stabilize your fuel.
If your Kubota lawn mower runs on diesel fuel, moisture and sediment in the fuel system can also cause corroding and clogging of the fuel components.
FIX: Use a siphon to drain your fuel tank into a container to collect the old fuel. Make sure it is a container designed for gasoline because plastics can degrade quickly and leak fuel. Set aside the fuel to be taken to an authorized recycling center to be disposed of.
Refill your fuel tank with a fuel including a fuel additive to stabilize your fuel. I use Sea Foam Motor Treatment in my lawn mower. There are many advantages including stabilizing fuel up to two years and cleaning your fuel system.
Plugged Fuel Filter on Your Kubota Lawn Mower
A Kubota uses a fuel filter to strain dirt and debris from fuel so they don’t enter the fuel system and cause damage to your fuel components and engine. I recommend replacing the fuel filter annually when completing a full service of your Kubota lawn mower.
A filter that isn’t changed regularly and becomes plugged with dirt and sediments can prevent fuel from passing through the filter.
FIX: Replace your fuel filter when you find it is plugged. Pay attention to the arrow on the plastic filter when replacing. The new filter must be installed with the arrow pointing in the direction of your fuel flow.
Clogged Fuel Lines on Your Kubota Lawn Mower
The sticky deposits that form from running old fuel can get lodged in your fuel lines causing a blockage. A block in the fuel line will prevent your Kubota mower from getting the fuel it needs. To find the clog in a fuel line, you need to check each section to isolate the section of hose with the problem.
FIX: Start and stop fuel flow using the fuel shut-off valve located at the bottom of your fuel tank. You can also use hose pinch-off pliers to clamp the line and stop flow. Check each section of hose by starting and stopping flow to see if fuel is still running out of the hose.
Once you find a section of hose that is clogged, remove the hose from your mower. Spray carburetor cleaner into the hose to help loosen the clog. Blow out the line with compressed air. Repeat until you dislodge the clog and open the line.
If you are unable to unclog the line or the fuel line is dry and cracked, it’s time to replace your fuel line.
Bad Fuel Pump on Your Kubota Lawn Mower
A Kubota lawn mower uses a fuel pump when the carburetor is positioned higher than the fuel tank. The pump is required to work against gravity to pump fuel up to the carburetor. Most lawn mowers use a vacuum fuel pump. This style pump builds pressure off the crankcase to pump fuel.
When the fuel pump cracks or fails to work correctly you will have to replace it. If you don’t see physical cracks or fuel leaking, you must take some troubleshooting steps to isolate the problem to your fuel pump.
FIX: Before you check your fuel pump, check to make sure you are getting fuel to the fuel pump. You may have completed this step already if you checked your fuel lines and filter for blockages, but if you didn’t, you need to start here.
Stop your fuel flow. Remove the fuel line off the inlet port of your fuel pump. Place the line in a container placed lower than the fuel tank and restart your fuel flow. If you are getting fuel out of the line and into the container, you have confirmed you have flow. If not, you need to find the blockage that may be in your fuel lines or fuel filter.
Once you have confirmed fuel flow to the pump, reattach the fuel line to the inlet port. Remove the fuel line from the carburetor and place it in a container. Check your pump is working correctly by starting your fuel flow and starting your mower. You should have a steady or pulsating flow of fuel coming out of the fuel line. If you do not, you need to replace your fuel pump.
If you have an injection fuel pump, get a pressure reading from the pressure hose using a fuel pressure gauge. Refer to your operator’s manual for Kubota’s specification for the fuel pressure. Replace the fuel pump if the pressures are lower than the specification.
Dirty Carburetor on Your Kubota Lawn Mower
A carburetor regulates the amount of air and fuel mixture needed to create a combustion in the engine. When the carburetor is dirty, clogging the small components inside your carburetor including the fuel jet, your Kubota mower isn’t able to get the fuel required to run.
FIX: First, identify if you need to take your carburetor apart to clean it. Make sure you are getting fuel to the carburetor. If you are not, check for a restriction in the fuel line, fuel filter or fuel pump.
Next, remove the air filter from the air filter housing. Spray carburetor cleaner into the air intake.
Start your engine to see if it will run. If your lawn mower starts and won’t continue to run, you will need to remove your carburetor and take it apart for cleaning. Check out this article for help with disassembling and cleaning the carburetor on your Kubota mower.
Bad Kubota Fuel Cap
A Kubota fuel cap is designed to vent allowing air to pass through the cap. The vent can become plugged and prevent airflow. When this happens, the fuel tank becomes a vacuum and doesn’t allow fuel to leave the fuel tank.
You may be able to determine whether your fuel cap is clogged by starting your mower and allowing it to run with and without the fuel cap. If the engine runs okay without the fuel cap, but eventually shuts off or begins to run sluggish with the fuel cap in place, you may have a plugged fuel cap.
FIX: You can attempt to clean your fuel cap to unclog the vent. If this doesn’t work, purchase a new Kubota fuel cap.
It’s important to take care of your fuel system to minimize the clogging and damage of your fuel components and engine. To protect your fuel system, you must start out using the right kind of gas. Simplicity gas-powered lawn mowers require an unleaded gasoline with a minimum octane-rating of 87 and a maximum 10% ethanol content.
Adding a fuel additive to reduce moisture and stabilize your fuel will help minimize clogging and running issues due to old fuel in your Simplicity.