11 Reasons Your John Deere Mower Starts Then Dies (Solved!)

You start your John Deere lawn mower and then it shuts off. You may have been able to mow for a while before it died or you might not have even been able to get it out of your garage.

Trying to find the cause of your mower problem can get very frustrating especially when you have exhausted checking everything you can think of.

A John Deere mower may start and then die when the engine is restricted of air or fuel caused by plugged filters, clogged fuel lines, bad fuel, or a dirty carburetor. A John Deere may also fail to run because of a bad spark plug, or bad ignition coil.

I have put together a full list of items to assist you in troubleshooting the problem with your mower shutting off.

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating.Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Reasons Your John Deere Mower Starts Then Dies

1. Bad Fuel in Your John Deere Mower

The quality of fuel you run through your John Deere can cause many different problems in your lawn mower including dying after it was running for a while.

Using bad fuel or fuel that has sat around in your mower for quite a while can cause clogging in your fuel system along with the degradation of parts.

Gasoline begins to break down and becomes less effective as soon as 30 days after purchase. It loses its ability to run well and hot because the chemicals added to fuel today, including ethanol, start to decay the fuel and cause it to separate.

Most types of gasoline on the market today include ethanol, an environmentally friendly corn-based product. Ethanol attracts moisture from the air which causes a sticky residue in the fuel tank that can clog the different elements that make up your fuel system.

You can read more about the effects of ethanol and the right fuel for your John Deere mower in this article.

Solution: If the fuel in your John Deere gas tank is old, drain and flush your fuel tank. Fill it will fresh fuel that includes a stabilizer and cleaner. I prefer a product called Sea Foam Motor Treatment to clean and stabilize my gasoline. You can read more about why it is my preference here.

Another fuel option is running ethanol-free fuel through your mower to avoid the effects of ethanol on your small engine. You can find ethanol-free fuel at some fuel stations sold as recreation fuel or REC-90. It is also available in canisters at your local hardware store. This option is quite pricey.

2. John Deere Mower Carburetor is Dirty

A dirty carburetor that is clogged can cause your John Deere to start and then die. Gummy material left behind by old fuel can clog your fuel jets and prevent the small parts of your carburetor from working properly.

Proceed with the following step to confirm your carburetor is the problem. Remove your air filter from the air filter housing and spray some carburetor cleaner into the air intake.

Attempt to start your mower. If it starts but doesn’t continue to run, you must take your carburetor apart and clean it.

Solution: Cleaning your John Deere carburetor isn’t that complicated of a procedure. If you are a little mechanical and don’t mind working with small parts, you should be able to handle cleaning your carburetor following the steps in this article.

If you choose not to clean your carburetor yourself, you can either bring your John Deere to your local lawn mower repair shop for cleaning or install a new carburetor.

3. Clogged Fuel Lines or Fuel Filter

Old fuel can cause blockages in your fuel lines and fuel filter restricting your engine’s access to fuel.

Solution: Use your fuel shut-off valve or crimp your fuel lines to start and stop the flow as you check sections of your fuel line for clogs.

Once you find a section that is clogged, spray carburetor cleaner in line to loosen the clog. Used compressed air to clear the clog from the fuel line.

If you are unable to remove the fuel clog, you must replace your fuel line.

4. Blocked or Broken Cooling Fins

Cooling fins on your John Deere exist to keep air circulating around your engine block or cylinder head. When the fins become plugged or broken, your engine can overheat and shut down after it has been running.

Solution: Clean around your fins and replace any broken fins. Remove debris around your engine. Be careful when working around a hot engine.

5. Too Much Oil in the Crankcase of Your John Deere Mower

When you overfill your engine crankcase with oil, increased pressure builds in the crankcase when the crankshaft and rod push through additional oil. This can cause your mower to overheat and shut down after running.

Another problem that can be created by running too much oil in your John Deere is oil getting into the cylinder through the valve train. This oil will begin to burn off and create smoke that can clog your air filter and cause your mower to shut down due to lack of air.

Overfilling your engine with oil can create additional problems that can cause significant damage to your lawn mower. Check out this article if you want to learn more.

Solution: To bring your engine oil to the correct level, drain a little oil until the oil level registers between the full lines on your John Deere oil dipstick. There are several methods you can use to drain a little oil.

Drain oil through the drain plug, from your oil filter, using an oil evacuator or a turkey baster (Yes, the kitchen utensil. Don’t reuse it for cooking purposes). Check and replace your air filter if you find it has been clogged by your engine smoking.

If you continue to have problems with your engine after correcting the oil level, have a small engine mechanic look at your engine to determine if running your engine with too much oil caused internal engine damage.

6. Plugged John Deere Air Filter

Your engine requires air to run. A plugged air filter will compromise the amount of air your engine receives and will cause it to run sluggishly. Your John Deere will even die after running for a while if your air filter is so plugged up with dirt it can’t access clean air.

It is important to check and clean your air filters several times during the mowing season. Not only can a plugged air filter cause your John Deere to shut down, but it can also cause internal engine damage resulting in a significant repair bill.

Solution:Clean Your John Deere Paper Air Filter Element

• Remove your air filter from the filter housing.
• Don’t let any dirt fall into the air intake. Wipe out any dirt that is left in the housing.
• Tap your air filter against a solid surface knocking out as much dirt as you can remove. Do not use compressed air to blow out your filter as this can damage it.
• Check to see if you can see light through the paper element by holding it up to a light source.
• Reuse your air filter if you see light. Replace it with a new air filter if you do not or if your filter is damaged or covered in oil.

7. Bad or Dirty John Deere Spark Plug

Running faulty or dirty spark plugs on your John Deere is another reason your mower can stop running. Your spark plugs may have been able to produce enough spark to start your mower, but it isn’t able to keep it running.

Remove your spark plug and check its condition. A dirty plug that has carbon buildup can cause your plugs to foul out causing intermittent running problems.

Solution: You can attempt to clean your spark plug, however an excessively dark or damaged spark plug must be replaced.

For future reference, it is a good idea to change your spark plug annually when completing your John Deere lawn mower service to reduce your likelihood of running problems due to a spark plug.

Before you move on to checking another potential cause for your John Deere dying while mowing, make sure your spark plug wires are secure and your spark plugs are gapped according to your engine manufacturer’s specifications.

8. Bad John Deere Ignition Coil

A bad ignition coil can cause your mower to die once it gets hot. The windings on the coil separate and short out. When this happens, the spark plugs are unable to get the voltage needed to work properly.

Solution: Identify a bad ignition coil using an ohm meter to check for a break in continuity. If you find a break, replace the coil.

9. John Deere Choke is in the Wrong Position

Make sure your choke is in the correct position. The choke is used to allow more fuel into the combustion chamber before the engine heats up by restricting air flow. The choke exists to help a mower start when cold.

If you leave your choke on after your engine starts and heats up, your engine will shut down when it continues to receive more fuel and less air.

10. Bad John Deere Mower Gas Cap

Your John Deere fuel cap has a vent that allows air to pass through the cap. When this vent is plugged, your mower will die after it starts. A clogged vent will cause your fuel tank to form a vacuum restricting fuel.

Solution: Loosen or remove your fuel cap and start your mower. If it starts and continues to run, replace the cap. Continue to allow it to run for a short period to see if your mower shuts down again. If it does shut down, there is a good chance the problem is in your fuel cap.

While you can try to clear the clog, you may end up needing to replace your cap with a new John Deere gas cap.

11. Clogged John Deere Mower Deck

A clogged mower deck doesn’t only affect your cut, it also can cause your engine to work hard and shut down. A deck that is plugged full of grass and dirt causes additional draw on your engine when it must work harder to turn your mower blade through the thick debris.

Adding dull mower blades to an already plugged mower deck can further magnify the load on your engine causing it to die and shut down.

Solution: Prevent this extra load on the engine by scraping your mower deck and sharpening your blades frequently.

Refrain from using your mower in wet conditions. Wet grass sticks to your deck and leaves clump in your yard.

In Summary

A John Deere lawn mower may start and then die because of items that can be prevented by performing routine annual maintenance on your mower.

Regularly checking your engine oil level and air filter condition in addition to scraping your deck and sharpening your mower blade is essential to keeping your John Deere working at its best.

If you continue to experience problems with your John Deere lawn mower, check out my list of common John Deere mower problems and solutions.

You may also need to contact your local John Deere dealership or mower repair shop for more in-depth problems that may be occurring in your mower.