John Deere L120 Problems (Issues, Reasons & Solutions)

John Deere L120 is a widespread name when it comes to lawn mowing. Regardless of how perfectly it does its job, it has some problems you will need to take care of. 

Hence, in this extensive guide, I am going to discuss all about John Deere L120 problems

On John Deere L120, the mower not starting or power loss are common problems. Replacing the spark plugs and tightening any loose cables will fix the not starting issue. To solve the power loss issue of the mower, you simply need to clean the deck well. And the problem should be fixed. 

Still not sure? Well, do not fret. Because, in this article, I have talked about it all. Also, I have put everything in a very easy-to-follow manner. 

John Deere L120 Starting Problems 

John Deere L120


One of the most frequent problems with a John Deere L120 is its inability to start. A riding lawnmower that all of a sudden won’t start could be the cause for your frustration.

It may happen due to a number of problems. Such as bad or no gas, a broken battery, a dirty fuel filter, spark plug troubles, and many more.

Different issues related to this starting problem of a John Deere l120 lawn mower are listed here.

Problems Reasons Solutions
Mower slowly turns with a clicking noise Faulty battery Tighten any loose cables. 

Clean the cables with wire brush to get rid of corrosion.

Attempts to turn over Worn-out spark plug Replace the spark plugs.
Has no movement Bad/no gas Fill the tank with fresh fuel.

Now let us see how to solve these, in detail! 

Problem 1: Mower Turns Over with a Clicking Noise

When a riding lawn mower won’t start, but when you turn the key, it turns slowly and makes a clicking sound. 


If your mower somewhat turns and makes a clicking noise, then your battery may be the cause of the problem. You need to figure out by now that it is happening due to a faulty battery.  


Here I have written down the solution in an easy-to-grasp method. Follow the instructions to fix the faulty battery: 

  • First of all, check the cables for any loose connections by jiggling them. Now utilize a wire brush to clean those well. 

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  • Lift the seat to check the batteries, and use an open-end wrench to tighten any loose cables. 
  • To clean, first, remove the negative cable, then use the brush to get rid of any corrosion that has accumulated. 
  • After that, reattach the cord and try to start the mower once more.

And your issue should be resolved. 

If this doesn’t solve the issue, you can check the battery’s voltage with a multimeter. Battery replacement or charging is necessary if the voltage is less than 12.7 volts. 

If your John Deere L120 requires a jump every time prior to mowing your lawn, it is another indication that the battery needs to be replaced.

Problem 2: Mower Attempts to Turn Over 

Sometimes you may notice that the lawn mower won’t start. However, it at least attempts to turn over. Also, it shows some kind of movement, at least instead of staying totally frozen. 


If you notice something like this with your John Deere L120, it is most probable that the spark plugs are the cause. The spark plugs are faulty. 


The solution for this issue is quite straightforward. Follow the easy and effortless fix given below:

  • Replace the spark plugs if you haven’t done it in a while to see if that solves the problem. 
  • If you just installed some new ones, look at them to see if they need cleaning or if anything is loose.

Spark plugs are frequently forgotten and need to be replaced every season or 100 hours. This will take care of your mower’s correct operation.

Problem 3: Mower Has No Movement

Often you might see your john deere l120 will have no movement at all. It is even more concerning but I have the ideal solution for you. 


There may be one probable reason for this. If the John Deere L120 won’t start, the fuel level may be low.

This is particularly valid if the lawnmower has been stored for more than 30 days. These machines have the potential to have more water than fuel in the tank while they are inactive for a while.


If you think this is the case, all you need to do is fill the tank with fresh fuel. And after a few attempts, the mower would start up normally.

But if the lawnmower has been sitting idly for 3 to 6 months, it has probably gone bad and needs to be replaced.

Alternatively, you might consider adding a fuel stabilizer.

John Deere L120 Electrical Problems

Another common problem with a John Deere L120 is its electrical issues. A riding lawn mower all of a sudden may lose power or the fuse may blow out.

Problems Reasons Solutions
John Deere Power Loss Problem Type of grass 

Cutting too much grass at once 

debris or grass clippings stuck underneath the mower deck

Lift up the mower deck slightly while cutting tall or thick grass.

Clean the deck properly. 

Fuse Blow Out Problem The PTO may be shorted Repair any wire damage. 

Keeping the PTO clutch disconnected, restart the engine. 

Problem 1: John Deere L120 Power-loss Problem

Another issue with the John Deere L120 mower is the power loss problem during mowing. If you are a user, you may have experienced the mower losing power while you are mowing. 


There may be a few causes if the power of your John Deere L120 riding mower starts to decline midway through the mowing task.

You should first evaluate the type of grass you are trimming because you might be trimming too much.

You can have debris or grass clippings stuck underneath the mower deck. 


First of all, see what type of grass you are working with. If it is tall or thick, then you should lift up the mower deck slightly to compensate.

Furthermore, make sure that you are not doing a couple of additional passes over that area. 

However, in case you are mowing short grass, it may be the issue with the deck itself. If so, a good cleaning of the deck is supposed to take care of the problem.

Problem 2: John Deere L120 Fuse Blow-Out Problem 

This is another electrical issue that John Deere L120 has. Your John Deere L120  mower keeps blowing fuses all of a sudden while in action. Now the blades will not even engage.


One reason for this may be that the PTO is shorted. Also, the wires leading to it are capable of rubbing through and shorting to the ground as well. It may lead to the mentioned issue of fuse blowout. 


The electric clutch (PTO), is bolted to the crankshaft of your engine. To check for damage, unplug the wires at the clutch and pull it back through the frame. 

Any wire damage needs to be repaired. Whether there is damage or no damage, make sure you keep the PTO clutch unconnected.

And restart the engine and keep an eye out for the fuse. This is to check if the fuse blows once more. Hopefully, it will not.  

Following it according to the above method shown should solve the issue. 

John Deere L120 Spitting Smoke Problem

It is very normal to panic if you notice smoke coming from the underside of your riding lawn mower. Your first response may be to panic. There is no denying that this is a terrifying and stressful situation.


Typically, this issue is caused due to the debris stuck in the mower deck. And it blocks the discharge.

Or sometimes it may be that the engine is not getting enough air. And as a result, it starts emitting smoke from underneath. 


If smoke is coming from underneath your John Deere L120, you should turn the mower off and dismount it right away. Taking a few steps back, you need to wait for it to cool down.

This problem may frequently be resolved by just cleaning the mower deck. This will also stop the smoke from happening again.

If it doesn’t, your blades might be the cause of the issue. Think about replacing them or getting a mechanic to look at it and try to fix it.

And if you follow these instructions thoroughly, the issue would be resolved!

John Deere L120  Excessive Vibration Problem

Another issue that is faced most often is the vibration issue of the John Deere l120. Sometimes there might be too much vibration encountered while turning on the engine.

It gets too frustrating for the user to work with something that is making too much noise and vibrating intolerably. 


It may happen due to various reasons. Here I have presented those.

Sometimes, the blades create a sound when they start to spin out of control. Because sound is produced via vibration, users find it irritating. In addition, the device’s destructive belt might also be the reason for this.

More frequently, it is possible to see the debris on the mower deck that is producing the loud noise.

The noise increases as the sheaves shift from their real position.


First of all, you must check the engine to see if it is in good or bad condition. You need to replace it if you get a red signal.

Then, you are going to inspect it to find if the mower has any attachments or not. For example, the cutter associated with the three times side hike can alter the blade’s motion.

The blade may have bent and become unbalanced by this point. So, you need to divide PTO in that case. It would get rid of or at least lessen the excessive noise and vibration. 

John Deere L120 Fuel Tank Capacity 

Fuel tank capacity normally refers to the amount of fuel that a certain vehicle fuel tank is capable of holding.

So, if you are a user of John Deere L120, this is one question you may have wondered about a few times.

How much fuel can a John Deere L120 hold? Well, a John Deere L120 Fuel Tank can hold about 2.1 gals 7.9 L of fuel.

John Deere L120 Horsepower 

Horsepower is yet another factor that you need to consider when buying a mower.

The L120 John Deere offers somewhat decent horsepower for a lawn mower. The rated net horsepower of the John Deere L120 is 20 hp (14.9 kW).

John Deere L120 Parts Diagram 

John Deere L120 is an easy-to-operate and easy-to-handle lawn mower. It offers a very effortless ride. The credit goes to all its parts being of good quality. All the parts combined make it an overall great lawn mower. 

John Deere L120 Parts Diagram



How many hours does a John Deere L120 last?

A John Deere L120 mower tends to have an average lifespan of eight to ten years. This should be about 4500 to 5000 hours of mowing over the course of your machine’s lifetime.

Is 100 hours a lot for a riding mower?

No, it is not. The majority of riding lawnmowers should last 500 to 1000 hours with the right care and maintenance. If properly maintained, more expensive riding mowers designed for bigger areas should last between 1000 and 2000 hours.

What is the best length to mow grass?

Make sure that you keep the grass at a height of 3 inches or a bit higher for a regular residential lawn. Mow your lawn before it grows to a height of 4.5 inches to maintain a 3-inch lawn. Also, when you mow, only take out about one-third of the leaf tissue and that should be perfect. 

Wrapping Up 

I Hope I’ve resolved all your queries of John Deere L120 problems. 

Now you have this comprehensive guide handy. From here you can point out the issue that matches your case. Then go for the solution. As I have explained everything here, it should not be a hassle. 

This is all for now. Have an awesome day!

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