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John Deere Lawn Mower Won't Start

The lawn mower small engine often has a separate model number. Use the small engine model number for a complete list of symptoms and parts. Watch our model # lookup video for help finding the model number.

LA105/42in Deck/Engine: 31P677-0239-B1

The 5 most common part(s) or condition(s) which contribute to the symptom Lawn mower won't start are listed below. Check or test each item and watch any available videos. If you are still unable to solve the problem you may need to do additional research and troubleshooting. Remember, with our 365 Days. Period.® return policy you can return any part for any reason. So, go ahead and buy it to try it. No other parts retailer offers this unconditional return policy.

For the symptom you selected, these are the most common parts or causes, ordered by the likelihood of fixing the symptom.

Grid is 1 inch square
Spark Plug - Part # 1605018 Mfg Part # 71G

Spark Plug

RepairClinic Item # 1605018 Aftermarket (Non-OEM) part

If the lawn mower engine does not start the spark plug might be defective. All small engines have an ignition coil. The coil is the device that provides spark for the spark plug(s). If the coil is bad power won't get to the spark plug(s). The coil is essentially a small, induction generator. It is mounted next to the flywheel. The flywheel has one or more strong, embedded magnets. As the flywheel spins, the magnet(s) zip past the induction coil, this action of a magnet passing past a coil induces a voltage. Depending on the design of the coil and the strength of the magnets, a stronger or weaker spark can be created and delivered to the spark plug(s). Each time the flywheel spins around a spark is generated. The best way to test a spark plug is to use a spark plug tester. The spark plug should have a strong, visible spark between the electrodes when the engine is cranking. If it doesn't, replace it.

Place your order by 8:00 PM ET and this item will ship out today - or it's FREE!

$2.55

Other Causes and Conditions

Old or Bad Gasoline

If the lawn mower does not start, the carburetor might be clogged or have old or bad fuel in the float bowl. If old or bad fuel was left in the lawn mower for a long time some of the volatile ingredients may have evaporated, leaving a thicker, stickier product that is more like varnish or shellac. This sticky fuel can clog up the small jets and ports in the carburetor and it can be difficult to burn making it hard to start the engine. The only solution is to drain the old fuel from the float bowl and thoroughly clean the carburetor with carburetor cleaner. If that isn't effective, replace the entire carburetor.

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Ignition Coil - Part # 2120381 Mfg Part # 799650

Ignition Coil

RepairClinic Item # 2120381

If the lawn mower engine does not start the ignition coil might be defective. All small engines have an ignition coil. The coil is the device that provides spark for the spark plug(s). If the coil is bad, power won't get spark to the plug(s). The coil is essentially a small, induction generator. It is mounted next to the flywheel. The flywheel has one or more strong, embedded magnets. As the flywheel spins, the magnet(s) zip past the induction coil, this action of a magnet passing past a coil induces a voltage. Depending on the design of the coil and the strength of the magnets, a stronger or weaker spark can be created and delivered to the spark plug(s). Each time the flywheel spins around a spark is generated. The best way to test the ignition coil is to use a spark plug tester to see if the spark plug is getting a spark. If it is, the ignition coil is working properly.

Place your order by 8:00 PM ET and this item will ship out today - or it's FREE!

$34.85

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Fuel Filter - Part # 1567939 Mfg Part # 691035

Fuel Filter

RepairClinic Item # 1567939

If the lawn mower does not start the fuel filter might be clogged. The fuel filter is usually inline with the fuel line coming from the gas tank. Its purpose is to trap sediment and contaminants from the fuel. Over time it can become clogged and not let enough fuel through. It can't be cleaned but must be replaced if needed.

Place your order by 8:00 PM ET and this item will ship out today - or it's FREE!

$5.85

Grid is 1 inch square
Fuel Filter - Part # 1974096 Mfg Part # 120-436

Fuel Filter

RepairClinic Item # 1974096 Aftermarket (Non-OEM) part

If the lawn mower does not start the fuel filter might be clogged. The fuel filter is usually inline with the fuel line coming from the gas tank. Its purpose is to trap sediment and contaminants from the fuel. Over time it can become clogged and not let enough fuel through. It can't be cleaned but must be replaced if needed.

 

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