3 John Deere Ignition Coil Problems

When it comes to reliable and sturdy farm equipment, John Deere is a name that farmers trust. However, even the most robust machinery can experience issues, and one of the common culprits in John Deere tractors and lawnmowers is ignition coil problems. 

As owners complained, the most common John Deere ignition coil includes sudden engine shut off, erratic ignition, and difficulty starting the mower. 

Whether you’re a seasoned farmer or an avid gardener with a trusty John Deere machine in your arsenal, understanding these common ignition coil problems will empower you to tackle maintenance tasks and keep your equipment running smoothly throughout each season. So, let’s see them in detail. 

John Deere Ignition Coil Problems

John Deere Ignition Coil Problems

John Deere ignition coil problems are a common issue that can lead to engine performance issues and prevent the lawn equipment from starting. The ignition coil is responsible for producing the electrical charge necessary to ignite the fuel in the engine, so any malfunction can result in poor or unreliable operation. 

1. Sudden Engine Shut Off

Have you experienced your John Deere lawn mower unexpectedly shutting off? If so, you are not alone. Many other owners have encountered this issue as well. Several owners have reported experiencing this problem multiple times. 

This occurrence typically prompts a thorough engine inspection to ensure it receives sufficient fuel. While the fuel supply appears to be in good condition, the underlying issue remains elusive. 

Despite installing an electronic ignition kit, a new distributor cap, a new coil, and new plug wires, the mower initially started but then stalled again. A test light connected to the coil revealed it was not receiving power when the engine shut off. 

The absence of an external resistor was also confirmed during troubleshooting efforts. Curiously, on one occasion, when the mower shut off and briefly shook, the test light illuminated once more, and the engine restarted. 

Various factors can lead to the issue of a vehicle running for a short time and then stalling. One unusual case is the failure of the gas tank cap to vent properly, which creates a vacuum that prevents fuel from reaching the carburetor. 

Another potential cause of this issue could be a restriction in fuel flow, such as a clogged fuel filter, varnish buildup in the line, or blockages in various parts of the carburetor caused by insects or leaves. 

While less common, condensers can also cause similar issues, with recovery being rare. According to experts, any interruption in the ignition primary circuit can lead to loss of ignition. The culprit could be a rusty fuse holder, a temperature-sensitive fuse, a switch, a wire, or a wire connection. 

Possible Solution:

A simple way to check for the gas tank cap venting issue is to remove the gas cap after the engine has stopped and observe if air rushes into the tank when the cap is loosened. It’s important to note that modern automotive caps do not vent, although they may fit correctly in other respects.

To diagnose fuel flow restriction, you can remove the float bowl drain plug (if present) and observe if there is a strong and continuous flow of fuel.

Additionally, if pulling on the choke causes temporary improvement in performance before stalling, it indicates that one of these fuel-related issues may be at play. If no drain plug is present, one can perform a similar flow test by disconnecting the fuel line from the carburetor inlet.

If all fuel-related issues are ruled out, it’s worth considering that ignition coils may also be responsible for causing loss of ignition after 10 or 15 minutes of running due to temperature-sensitive internal faults.

However, in the case of a circuit or power supply-related issue, a test light is more effective than a voltmeter for identifying poor connections, as it draws more current. 

When troubleshooting a circuit issue, testing at the midpoint of the wiring is the quickest way to locate the problem. If there is good power, test at the midpoint of the last half; otherwise, test at the midpoint of the first half. 

This process should continue by dividing into halves until the issue is isolated. Known as Binary Chopping, this technique is also a superfast search method for sorted data in computer files.

2. Unusual Firing/Ignition on the Rear Spark Plug

Owners of Jon Deere lawn mowers, particularly those equipped with the Kawasaki 25hp engine, have encountered an unusual issue. They have observed that the engine occasionally fails to ignite properly on the rear plug. 

Initial attempts to address this problem involved cleaning and adjusting the plug, but these efforts proved ineffective. Substituting the plugs also did not yield any improvement, indicating that the issue does not lie with the plug itself.

A preliminary assessment suggests that a faulty connection, a malfunctioning ignition coil, or an incorrect air gap could be responsible for this irregular firing. 

Upon further investigation, it has become apparent that the ignition coil is designed to self-energize and is being obstructed by grounding in this particular scenario. Therefore, it is likely that either one of the coils is defective or there are issues with the wires connected to the coil.

Possible Solution:

To diagnose the issue, initiate a test by disconnecting the wire from the coil (or both coils) while running. Subsequently, remove one spark plug wire and observe if the engine continues to operate. 

If it ceases to function, it indicates that the cylinder on the opposite side is not firing and may indicate a faulty ignition coil. However, if it continues running, it suggests an issue with the side from which you removed the wire.

Avoid operating your mower during this period. If eliminating the misfire resolves the problem, then there is likely a wiring issue—specifically regarding connecting both coils. Conversely, if removal persists even after troubleshooting steps have been taken, it could indicate either a defective coil itself or a problem related to a valve cap.

3. The engine Cranks but Does Not Start

The third and most annoying issue related to the ignition coil in John Deere lawn mowers is the engine cranking but failing to start. This problem is common with these mowers, making the ignition coil the primary component to investigate. 

In some cases, a faulty relay mounted on the side of the motor may also cause issues with the spark plugs firing correctly. It’s important to note that while this scenario is less likely, it should still be considered as a potential cause for the problem.

Possible Solution:

When troubleshooting a crank but no start situation, begin with a thorough inspection of the ignition coil and its connections. Look for signs of damage, such as cracks, corrosion, or loose wiring. 

Testing the resistance of the coil using an ohmmeter can also help identify potential faults. In cases where preliminary checks indicate normal ignition coil function, turning attention to the relay would be prudent. Besides, verify the gasoline level. 

Subsequently, ensure that the throttle choke is appropriately positioned, as detailed in your owner’s handbook. Finally, investigate the spark plug and ignition wire, as they could be responsible for recurring issues.

The spark plug plays a crucial role in engine operation, and any malfunctions may lead to other problems. Therefore, confirming that both components are in optimal working condition is imperative.

Final Words

John Deere ignition coil problems can be a significant source of frustration for tractor owners. From issues with misfiring and stalling to difficulties starting the engine, these problems can majorly impact productivity and efficiency. 

However, by understanding the common causes of ignition coil issues and learning how to diagnose and address them, tractor owners can effectively mitigate these challenges. 

Regular maintenance, including cleaning and inspection, is crucial for preventing potential ignition coil failures. By staying informed about these common problems and taking proactive measures to address them, tractor owners can ensure optimal performance from their equipment.

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