Why Does John Deere L120 Won’t Crank? All Reasons In One Place

by Jack Grover
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Why John Deere L120 won’t crank? There are many possible causes for this problem. The primary reasons are the wrong mower operation process and issues with the mower’s fuel system like fuel line, fuel pump, fuel filter, etc.

It isn’t enjoyable to get your lawnmower to stop and stop cranking suddenly. Several parts need to be checked to identify a specific reason if this situation occurs. But it is not a fact to worry about because it is simple to fix issues.

Know the possible reason John Deere stopped working and learn the required fixes.

Reasons & Fixes When John Deere L120 Won’t Crank

John Deere’s mower may not start for several reasons. The fault can be in the fuel system parts or the parts that ignite the engine to start the mower. Problems can be with the battery or charging system too.

Faulty fuel cap, fuel pump, or ignition coilReplace the defective fuel cap or pump or ignition coil
Clogged fuel filter, air filter, carburetor, or fuel lineClean the fuel or air filter or fuel line or carburetor
Empty fuel tank or wrong fuelFill the fuel tank with fresh fuel
Faulty spark plugs or starter solenoidReplace the spark plug or solenoid
Faulty battery, charging system, or safety switchesReplace battery or terminal or charging system or switches
Wrong operating procedureFollow the correct operating procedure as mentioned in the manual

Inappropriate Operating Procedure

There are specific safety procedures to start, run, and stop the John Deere mower. Your mower will shut down if you fail to follow the process within the proper steps.

Solution: If you have an issue with starting your mower, check the manual first and ensure that you are following the correct procedure. If you find that you are doing right, then go for the subsequent checking.

Empty Fuel Tank in John Deere L120

It is a common reason that the John Deere tractor won’t start. But we forget this simplest factor and go to check other matters. If we try to crank the tractor with an empty fuel tank several times, it can develop a fuel leak.

Solutions: First, check the fuel tank status when you get problems with the John Deere. Fill it with fresh gasoline or diesel as required soon.

Bad or Expired Fuel

Gasoline has a short shelf life. Generally, it expires within 30 days. After this period, gas or fuel starts to break, and its effectiveness reduces. On the other hand, modern gasoline has ethanol, which quickly evaporates with time. The residue of the gas blocks the fuel system. It makes the John Deere L120 hard to start.

Solution: When you find that the fuel is terrible or expired, could you remove it from the tank by a fuel pump? Then fill the fuel tank with fresh energy and fuel additive. The fuel additive works as a cleaner of the fuel system. Using new fuel within 30 days is the best practice.

Defective Fuel Cap

The fuel cap in the fuel system has a vent. If the fuel cap is broken or faulty, its vent cannot work. It will make a vacuum, preventing the fuel from running to the engine from the fuel tank. That’s when the John Deere L120 does not crank.

Solution: First, you must ensure that the problem is with the fuel cap. So, remove the cap and try to start the mower. If it starts, reinstall the cap and continue running the mower. If you have a problem again, repeat the cap removing process. It will confirm that the problem is with the fuel cap.

You must replace the fuel cap and install the new one.

Clogged Fuel Filter

Fuel filters ensure that the engine is getting clean fuel. The dirt or contaminants if filtered when the fuel is running through it. So, it is evident that the filter can be clogged. Enough fuel cannot pass through the filter if it is blocked. Then the engine stalls and the John Deere L120 won’t crank.

Solution: When the filter is clogged, replace it and install the new one. It is not good to clean the filter and reuse it.

Faulty Fuel Pump

The fuel pump in the John Deere mowers pumps the gasoline into the carburetor. The pump is located under the carburetor. This pump uses three ports where one port lets the fuel out of the tank toward the carburetor, the second port lets the fuel run into the fuel tank, and the third one creates the pressure that pushes the fuel to the carburetor.

All three ports are necessary to maintain the fuel flow in the fuel system. If one of the ports or the fuel pump is broken or faulty, the mower cannot turn over.

Solution: Check the fuel pump carefully to see if there is any crack in the ports or the fuel pump. If the port is broken, you must replace the fuel pump with a new one. After installing a new pump or repairing the old fuel pump, check if it works properly.

Check the fuel flow after turning off the fuel valve and fuel inlet port. If the outlet fuel pump port does not work, it causes problems with the fuel flow. Then you have to check the fuel filter or fuel lines. If there is no issue, set the fuel system right and run the mower to ensure it is running correctly.

There can be leaking in the pump. If you find the leak, replace the pump.

Blockage in Fuel Line

If the John Deere mower is running on old fuel or wrong fuel, it leaves some gummy residue on the fuel line. It can cause blockage in the bar and restrict the fuel flow. It will stop the mower from starting over.

Solution: First, check the fuel line and locate the blockage. Then turn the fuel flow off and remove the fuel line from the system. Now clean it using the carburetor cleaner and the compressed air. After cleaning the tube, reinstall it.

If the clogging part is stubborn or the fuel line becomes dry and begins to crack, replace the entire line.

Clogged Carburetor

The carburetor controls the fuel quantity to be mixed with the air for combustion. The dirt and contaminants can block the carburetor. Then it will not work well, and the engine will not get the necessary fuel and air mixture to start the mower engine.

Solution: Remove the carburetor from the fuel system and clean it using the carburetor cleaner. If the carburetor is too bad and it is not possible to clean it properly, you have to replace it and install a new one.

Faulty Starter Solenoid

The starter solenoid is the electromagnetic switch to control the turning on and off of the starter motor of the mower engine. If it is terrible, the mower cannot start.

Solution: If this switch is faulty, you will get a clicking or humming sound from the ignition key. Another indication of the defective solenoid is the wire melting smoke coming from solenoid parts.

If it is wrong or you get these symptoms, replace the solenoid immediately.

Clogged Air Filter

To run the John Deere mower, the air must be clean. The air filter works continuously to provide clean air to the engine. So, the air filter can be clogged with dirt. Then the machine will not get the clean air supply and causes problems with starting or stopping suddenly.

Solution: A clogged air filter should be cleaned by removing it from the air filter system and reinstalling it. The air filter can be faulty after a specific time. Check the filter by holding it to a light source. It isn’t very accurate if the light cannot pass through it. You have to replace it right away.

Also Read: John Deere Hydrostatic Transmission Problems

The clogged air filter can create further problems for the engine. It is good to check and clean the air filter within a specific time interval. You should replace the air filter every year.

Faulty Battery or Terminals

If the mower battery is dead and the connections are loose, the mower will not crank. The corrosion in terminals causes issues with the engine start.

Solution: If the terminals are dirty, clean them using the baking soda mixture and wire brush. If the battery is dead, charge it using the charger. The battery may not be able to hold a charge. Then you have to replace the battery.

Problem with Charging System

When the charging system itself is faulty, it can drain the battery. In turn, the mower will not start. A stator or alternator can cause it.

Solution: If the charging system is faulty, you must replace it. But you should take the professional mechanic’s help because the parts are expensive and throw these parts after becoming sure that the problem is on that part.

Faulty or Loosely Connected Spark Plug

A spark plug can be defective or dirty or get carbon buildup or cracks. Besides, it can be loosely connected, creating an improper gap. These issues will cause problems with John Deere starting. A faulty or dirty spark plug can cause an engine to misfire.

Solution: Check the spark plug and find the problem. If it is dirty, you can reuse it after cleaning it with a wire brush. If it is not correctly connected, repair or fix the connection and use it again. But the defective or broken spark plug cannot work, and you have to replace it.

Faulty Ignition Coil

The ignition coil is the voltage supplier to the spark plug. In the absence of the voltage, the spark plug will not fire, and the engine will not start.

Solution: When you are sure that the spark plug is correct, check the ignition coil. If it is terrible, you must replace it.

Faulty Safety Switch

There are some safety switches to keep the rider safe. For example, a button kills the engine if the rider leaves the mower in some emergency. If one of the safety switches is faulty or wrong, the mower will not start. John Deere mowers are designed to ensure the mower user’s safety.

Solution: When you find a problem with the mower starting, check the safety switches within other checks. If you find the wrong switch. Immediately replace it.

This Video Will Help You Too!


Frequently Asked Questions (FAQs)

Why would a John Deere tractor not start?

There are many parts in the fuel running system and engine starting function. If any part is faulty or clogged, or dirty, it will be unable to supply necessary things, and the mower won’t crank. For example, there are fuel pumps, fuel lines, fuel filters, fuel tanks, fuel caps, etc. if one of these parts is defective, it will create a problem with the engine starting function.

Why is my John Deere mower not turning over?

Though it is unacceptable to get the John Deere lawnmower to stop cranking, it happens. The reasons are in the engine system parts like the fuel system, ignition coil, spark plugs, air filter, safety switches, etc. When one of the parts is broken or disconnected or fails to work appropriately, the engine cannot work.

How do you start a John Deere L120 lawn mower?

When you find starting the John Deere L120 lawn mower hard, you must go through specific checking steps. First, ensure that you are using the correct procedure to run the mower. If it is okay, check the fuel filter, fuel pump, fuel cap, fuel lines, fuel tanks, fuel status and condition, air filter, safety switches, ignition coil, spark plug, battery terminal, charging system, etc. If found anything issues with these parts, fix them and run your mower.


Why my John Deere L120 won’t crank? It is a common question for many John Deere lawnmower users. That’s why you should go through this article and know the reasons so that you can find out issues quickly and fix them immediately.

When one part of the system cracks or is faulty or clogged, you should not wait and sit on the mower to repair the issue later. You should fix the problem as soon as possible.

Besides, you should be careful about the regular maintenance of the lawnmower, like cleaning and replacing the fuel filter and air filter at a particular time interval, checking the fuel pump if it is working correctly, preventing the connections or battery, etc.

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