17 Reasons John Deere Mower Won’t Start

John Deere Mower won't Start

John Deere mowing tractors are some of the most reliable lawn care machines. However, they are not exempt from breaking down. Sometimes your John Deere mower won’t start.

When this happens, you will need to know how to troubleshoot the mower, isolate the problem, and fix it.

Knowing where to look when your John Deere lawnmower fails to start can make all the difference.

If the problem interrupts your work, knowing how to fix it can help keep you from losing valuable lawn care time.

This article looks at seventeen possible reasons likely to prevent John Deere lawnmower from starting.

Why John Deere Mower won’t Start?

Your John Deere mowing tractor may not start if it has an empty gas tank, bad fuel, bad engine, faulty safety sensor, bad battery, faulty charging system, defective spark plug, clogged air filter, or a dirty carburetor.

A clogged fuel filter, gas cap malfunction, or a bad fuel pump can also be responsible for the failed start.

Any of these problems likely to keep your mower from starting can be diagnosed and fixed with simple solutions, except for the few cases requiring some mechanics knowledge.

Read along to learn about these common problems.

1. Bad fuel in the John Deere mower

Gasoline, which your John Deere lawnmower uses, remains serviceable for only 30 days after purchase.

Ideally, the fuel starts breaking down within only a few weeks but eventually becomes unusable after 30 days.

What happens is the ethanol in your gasoline attracts moisture and begins to settle at the bottom of your mowing truck’s gas tank.

Then, as time goes on, the water evaporates, leaving behind a sticky residue. If your gas tank has gasoline older than 30 days, it will not work.

You could have a full tank of gas, but if the fuel is bad, it will not fire up the engine and run it.

So, the first thing to do when your John Deere lawnmower doesn’t start is to check how long you have had the gas in your mower tank.

What to do

The only solution to degraded gas is to drain it and replace it with fresh fuel. To remove bad old fuel from your gas tank, you can use a fuel siphon pump.

Once you have fresh fuel in the tank, consider adding a stabilizer if you intend to leave it in the mower for more than a month.

Fuel stabilizers are formulated to remove the moisture responsible for degrading your gasoline. This way, the fuel can remain serviceable for as long as six months.

Alternatively, you can buy gasoline with a stabilizer already added to keep it from going bad too soon.

2. An empty gas tank in your lawnmower

If you have no gas in your lawnmower tank, your mower will not start. While this may appear too obvious to happen, many lawnmower owners run out of gas without notice.

So, do not be surprised if it happens to you. Your gas tank can also run empty due to a fuel leak. So it is best not to rule out the possibility of an empty tank even if you recently refilled it.

What to do

Check the gas tank. If it is empty, refill it with the correct fuel type. If your mower uses gasoline, get it some. Ensure you don’t use a different fuel type than the one designated for your engine.

For instance, do not try filling your gas tank with gasoline if you have a diesel engine. While refilling the tank, consider inspecting it for any leaks you might have developed.

If you find one, you may have to replace the tank altogether. Such leaks are rare, but they can occur nonetheless.

3. Faulty John Deere spark plug

Spark plugs produce a spark or electric beam that starts the combustion in your John Deere mower’s engine.

Over time, this crucial component can develop carbon buildup or other faults keeping it from working correctly. Bad spark plugs plug will not produce the needed spark, resulting in no ignition.

The crankshaft in your engine requires this initial ignition to start moving. So without it, there will be no combustion and the engine will not turn over.

The spark plug can also malfunction due to physical damage or loose connections. Regardless of which fault causes the spark plug to malfunction, your engine will not start.

How to fix the problem

Visually inspect the bad spark plug on your John Deere tractor to see if it is damaged. You should see if it has a film of carbon or excessive dirt covering it.

Dirt buildup should be easy to fix. Cleaning the buildup with a wire brush should allow the spark plug to work again. You will also be able to see if the wires connecting the spark plug are loose.

Your spark plug may also be gapped incorrectly. You can determine the proper gapping for your mower’s spark plug by referring to the owner’s manual.

Once you have the correct gaping information, check it against the plug to see if it is the issue to set it correctly with a feeler gauge.

However, if the component is damaged, the alternative is to replace it with a new one. Ensure you follow the manufacturer’s specifications when gapping the new spark plug.

4. Fuel cap malfunction

The fuel cap on your John Deere riding mower has a vent that lets in air to balance pressure within the gas tank.

If this vent is blocked or the tube is broken, the resulting vacuum inside the gas tank will prevent fuel from coming out.

As a result, the engine will not receive the fuel it needs to run, causing the mower not to start. A clogged fuel cap vent causes the same problem as an empty gas tank, depriving the engine of fuel.

Solution

Diagnose the problem by removing the cap and trying to start the engine. If the mower starts and then stops, reinstall the gas cap and let the mower continue running.

If a clogged gas cap vent is the problem, the engine will start choking and die eventually.

Replace the damaged gas cup with a new one from your local dealership or Amazon to fix the problem.

5. Bad fuel pump

Your mower is typically designed to have the gas tank located lower than the carburetor. Therefore, the gas pump is required to move the fuel from the tank to the carburetor.

Naturally, if this vacuum pump fails, the fuel will not reach the carburetor, causing the engine to misfire.

Possible fix

Start by visually inspecting the pumping component for noticeable cracks. The pump uses pressure from the crankcase to draw the fuel in via its inlet valve and out via the outlet valve.

If it is cracked, the gaps will create a pressure leak, making it unable to draw the gas in or push it out. The solution is to replace it.

Further, check if the fuel is coming out of the gas tank into the pump. To do this, crimp the fuel line using pinch pliers or simply close the fuel valve.

Once that is done, detach the line from the fuel pump. Place it in an empty container and start the flow by removing the pinch pliers or opening the valve.

You want to check to see if fuel comes out of the pump into the container to confirm that the problem is with the pump and not the tank.

If no fuel flows into the container, you might be staring at clogged fuel lines or filters.

However, if fuel flows into the container, meaning the pump is getting gas from the mower’s tank, reconnect the fuel line to the pump’s inlet port.

After that, disconnect the gas tube from the carburetor and place it in an empty container instead. Start the mower and observe if fuel comes out into the container.

A steady flow or pulse of gas into the empty container will mean the pump is working well. However, if the pulse or fuel flow is inconsistent, you have a bad pump that needs replacement.

6. Plugged John Deere air filter

Just like anything that breathes, the engine requires air for its combustion and operation.

The air filter helps clean the air before it reaches the engine to prevent dirt and other contaminants from reaching and damaging the engine’s inner components.

However, the filter can get clogged over time, cutting the engine’s supply of fresh air.

If this becomes too serious, the engine will not receive the air it needs to work, preventing the mower from starting and running.

This problem is highly likely if you operate your John Deere mower in dusty conditions.

Solution

You can fix the problem by cleaning or replacing the air filter, depending on how clogged it is.

Start by carefully removing the filter from its housing and tapping it on a solid surface to force the dirt out.

If the blockage is only moderate, tapping the paper air filter against a solid object will remove the dirt and allow you to reuse the filter.

Hold it against a light source to see if the sight is shining through it. If not, the damage is serious, and you must replace the filter altogether.

However, if you can see the light shining through the filter, it is clean, and you may return it to its housing for reuse.

7. A dirty carburetor on your John Deere mower

The carburetor is the component that regulates the amount of fuel that mixes with air for combustion in the engine.

If you use old fuel in your John Deere mower, it can leave sticky residues in the carburetor over time.

A dirty carburetor has clogged components including the filter and air intake that cannot perform their function as required.

This can cause the engine to misfire, preventing your lawnmower from starting and running.

What to do

If you have some knowledge of mechanics, locate the carburetor, take it apart and clean its clogged components. Once done, reassemble the device and test it for reuse.

If a dirty carburetor was the problem, your John Deere mowing tractor should work well after cleaning the carburetor.

However, if you are not confident or up to the task, you can hire a professional mechanic to clean the device for you.

If you are convinced that the carburetor is in bad shape, consider replacing it with a new one.

8. Clogged fuel filter

Dirty fuel often has different kinds of contaminants, including organic and particulate contaminants. All of these can end up in the gas filter that keeps them from reaching the engine.

Running old fuel in your mower also leaves behind sticky residues that typically end up in the filter. Over time, these residues can clog the filter, restricting the passage of fuel into the engine.

A blocked fuel filter can prevent the engine from receiving fuel, causing it to misfire and preventing the mower from starting.

How to fix the problem

Once the fuel filter is clogged, you must replace it to restore normal operation. Ensure you pay attention to the direction of the fuel flow when installing the new filter.

There should be an arrow indicating this direction to help you install the component correctly.

9. Blocked fuel line

The other part directly affected by dirty fuel and residues that old fuel leaves behind is the fuel hose.

Your John Deere mower has several fuel hoses, including one from the gas tank to the fuel pump and another from the pump to the carburetor.

When you use old or dirty fuel in your mower, residues can be deposited on the walls of these fuel hoses.

Over time, the blockage can accumulate and restrict the flow across the mower’s fuel delivery system.

What to do

If you suspect gummy deposits from old fuel are restricting the gas flow through your fuel line, crimp the fuel hose or stop the flow using the fuel shut-off valve and inspect the tube for a blockage.

Once you identify the blockage, remove the affected fuel hose from the mower and spray it with a carburetor cleaner to undo the clog.

After loosening the blockage with a carburetor cleaner, remove the residue by blowing compressed air through the tube.

You may have to repeat the process several times to remove all the residue blocking the hose.

10. John Deere starter solenoid malfunction

As the name suggests, the starter solenoid in your John Deere mower acts as the switch that starts your mower.

It provides the electromagnetic energy required to turn over the engine by actuating the mower’s starter motor.

You can tell there is a problem with the solenoid if you hear a humming or clicking sound when turning the key in your ignition. This is a common problem with John Deere 5055e.

The cable attached to the bad starter solenoid can also get hot and begin to smoke if the solenoid has a problem.

If you see any of these symptoms, your john Deere mower may have a bad solenoid.

What to do about it

Test the solenoid according to the instructions in your owner’s manual. If the component is bad, replace it with a new one.

11. A bad battery on your John Deere mower

Your John Deere mowing tractor requires the battery to produce the initial electrical current to ignite the engine.

If the battery is not working, the engine won’t start, and the mower won’t work. If the battery is old, it might not be holding charge as it should.

Ideally, the battery needs to hold a minimum charge of 12.7 volts to be considered suitable for operating the John Deere mower.

A bad battery could also have another form of damage, including a buildup of corrosion on the terminals. Any such fault can prevent it from starting your engine. This problem is common with John Deere Z225.

What to do

Use a multimeter to test the battery for the flow of electrical current. If the reading is below 12.7 volts, charge the battery and test it again.

If the reading is still below 12.7 volts after charging it, replace the battery with a new one to fix the problem.

12. Loose battery terminals

Sometimes loose battery terminals can cause the battery not to work and power up your john Deere mower.

The battery connects to the mower via the positive and negative terminals. Both terminals must be secure for the battery to work.

Any loose terminal will break the flow of electrical current or make it unsteady. So, diagnose the problem by checking if you have any loose battery cables.

Solution

If you find that one or both terminals are loose, you should fix the problem easily by tightening the bolt securing that terminal.

This should restore a steady flow and make your lawnmower work well again.

13. Malfunctioning safety switch

The lawnmower has several safety switches designed to ensure the operator’s safety. One of their roles is to turn off the engine if you leave your seat with the mower deck engaged.

If this safety switch malfunctions, it will send the wrong signal to the control panel, preventing the engine from starting and running even if you follow the correct operating procedure.

How to fix the problem

Refer to your owner’s manual and follow the instructions provided to bypass the safety switch function.

Once you have identified the bad switch, replace it and reconnect the switches before you resume operating the mower.

14. Bad ignition switch

If you get no response when you turn the key in your mower’s ignition, the ignition switch may be the culprit.

The lawnmower won’t start with a bad ignition switch until you fix the problem.

What to do

Use a multimeter to check if the switch is working properly. If it does not transmit the current, replace it with a new one to fix the problem.

15. A worn ignition coil on the John Deere lawn mower

The ignition coil in your John Deere mower channels the needed electrical current to your spark plug. The spark plug then creates the electrical beam that ignites the engine.

If the ignition coil malfunctions, the spark plug will not receive the current to fire the engine, and the mower will not start.

Solution

Start by checking for continuity in the suspect ignition coil using an ohmmeter. If there is a break in continuity, replace the faulty ignition coil.

16. Incorrect starting procedure

Your lawnmower comes with a standard operating procedure to ensure you can start and operate it safely.

If you skip or ignore any of these procedures specified in your operator’s manual, the mower will likely ignore you too.

What to do

Check your operating manual and familiarize yourself with the proper operating procedure for your John Deere lawnmowers.

Follow the specified steps to ensure you start the mower correctly to keep its safety features from shutting it off.

17. Seized John Deere engine

Sometimes the engine itself can malfunction. For instance, parts such as the engine’s piston rings can get broken, keeping them from properly sealing the fuel-air mixture in their respective cylinders.

Such breakages will likely cause the piston rings to lose compression. Such problems causing a failed engine are less common than the rest of the problems discussed here, but they can occur.

The engine can also be seized, especially if you rarely change the oil or service it.

How to fix the problem

Have a mechanic take apart the engine and check parts like the piston rings for noticeable damages. Once found, replace the damaged parts.

FAQs

Why is my John Deere cranking but not starting?

A clogged air filter is the most likely reason your John Deere mower cranks without starting. The problem prevents the engine from receiving the right amount of fresh air needed to fire up the engine and keep it running.

What will cause a mower to start and then dies?

Problems that will cause a lawn mower to start and then die right after start include low fuel in the gas tank, a bad choke, or a broken gas cup valve. The problem could also result from a damaged spark plug or malfunctioning fuel pump.

What do you do when your John Deere mower doesn’t start?

The first thing to do when a John Deere mower won’t start is to check if you have enough fuel in the gas tank. An empty fuel tank is among the most common reasons your mower won’t start.

Final Thoughts

If you own a John Deere lawn mower, prepare to encounter various problems over the lifetime of the mowing vehicle.

While some of these problems may cost a significant amount of money to fix, most of them causing the mower not to start will likely cost nothing to fix on your own.

We hope this guide helps you learn how to identify and fix some of the most common problems keeping John Deere lawnmowers from starting.

Let us know your thoughts in the comments.