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John Deere Replacement Part Lawn Mower is Hard to Start

The lawn mowersmall 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.

JS35/Engine: 126T07-0132-B1

The part(s) or condition(s) listed below for the symptom Lawn mower is hard to start are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.

Most Frequent Causes for Lawn mower is hard to start

Cause 1Primer Bulb

Over time, the rubber of the primer bulb can become brittle and cracked. If the primer bulb is cracked, air will get into the fuel system and cause the engine not to run properly. If the primer bulb is cracked, replace it.

Parts
Primer Bulb for your John Deere Replacement PartLawn Mower
Primer Bulb - Part # 1567970 Mfg Part # 694395

Briggs & Stratton carburetor primer bulb. The primer bulb draws fuel into the carburetor to make the engine easier to start.

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Cause 2Carburetor Repair Kit

The carburetor might be clogged. A clogged carburetor is most commonly caused by leaving fuel in the hedge trimmer for a long period of time. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and make the engine hard to start. If the carburetor is clogged, try cleaning it with carburetor cleaner. If cleaning the carburetor isn’t effective, rebuild or replace the entire carburetor.

Parts
Carburetor Repair Kit for your John Deere Replacement PartLawn Mower
Carburetor Repair Kit - Part # 1567909 Mfg Part # 498260

Briggs & Stratton Original Equipment 498260 Carburetor Overhaul Kit. If the carburetor is clogged, the engine won't get enough fuel. As a result, the engine may not start or may run poorly.

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Cause 3Old or Bad Gasoline

There may be old or bad fuel in the carburetor float bowl. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and make the engine hard to start. If the carburetor is clogged, try cleaning it with carburetor cleaner. If cleaning the carburetor isn’t effective, rebuild or replace the entire carburetor.

Cause 4Spark Plug

Inspect the spark plug for signs of wear or damage. If the porcelain insulator is cracked, an electrode is burned away or damaged, or there is heavy carbon buildup at the electrode, replace the spark plug. To determine if the spark plug is defective, use a spark plug tester. You should see a strong spark between the tester’s terminals when the engine is cranking. If there is no spark, this indicates that the spark plug is defective and should be replaced.

Parts
Spark Plug for your John Deere Replacement PartLawn Mower
Spark Plug - Part # 1568001 Mfg Part # 796112S

Briggs & Stratton Spark Plug (RJ19LM). If the engine does not start or runs poorly then the spark plug may be defective and will need replacement.

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Cause 5Flywheel Key

If the generator engine won’t start, the flywheel key might have sheared in half. The flywheel key is a small metal piece which fits into the crankshaft and engages with the flywheel. If the generator engine stops suddenly, the flywheel key may break in half. To determine if the flywheel key is broken, remove the flywheel from the engine and inspect the flywheel key. If the flywheel key is broken, replace it.

Parts
Flywheel Key for your John Deere Replacement PartLawn Mower
Flywheel Key - Part # 1567829 Mfg Part # 222698S

Briggs & Stratton flywheel key. The flywheel key aligns the flywheel in the correct position on the crankshaft. If the engine stops suddenly due to hitting a hard object, the flywheel key shears in half to prevent damage to the engine. If the flywheel key is broken, the engine won't start.

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Cause 6Ignition Coil

The ignition coil sends voltage to the spark plug while the engine is running. If the ignition coil is defective, the engine may be hard to start. Before replacing the ignition coil, ensure that the spark plug is working properly. If you have confirmed that the spark plug is working properly, test the ignition coil with an ignition coil tester. If the ignition coil is defective, replace it.

Parts
Ignition Coil for your John Deere Replacement PartLawn Mower
Ignition Coil - Part # 2119869 Mfg Part # 590454

Ignition coil. The ignition coil sends voltage to the spark plug while the engine is running. If the ignition coil is defective, the engine may not start. If your engine was built before date code 101230xx, you will need to order a new Governor Arm see Related Items below.

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Cause 7Fuel Filter

The fuel filter might be clogged. A clogged fuel filter is most commonly caused by leaving old fuel in the lawn mower. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the fuel filter and make the engine hard to start. If old fuel was left in the lawn mower, drain the old fuel from the fuel tank and replace the fuel filter.

Parts
Fuel Filter for your John Deere Replacement PartLawn Mower
Fuel Filter - Part # 1610709 Mfg Part # 394358S

Briggs & Stratton in-line fuel filter. The filter screen is on the large side of the housing. The port on the large side goes to the fuel tank while the port on the small side of the housing goes to the carburetor.

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Cause 8On - Off Switch

To determine if the on-off switch is defective, use a multimeter to test it for continuity.

Parts
On - Off Switch for your John Deere Replacement PartLawn Mower
On - Off Switch - Part # 1611082 Mfg Part # 692310
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Cause 9Recoil Starter

When the starter rope is pulled and released, the recoil spring recoils the starter rope onto a pulley. If the recoil spring is broken, the rope won’t be able to recoil onto the pulley. As a result, the engine won’t start. Many recoil springs can be replaced individually, but it may be easier to replace the whole recoil starter assembly.

Parts
Recoil Starter for your John Deere Replacement PartLawn Mower
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Cause 10Recoil Starter

When the starter rope is pulled and released, the recoil spring recoils the starter rope onto a pulley. If the recoil spring is broken, the rope won’t be able to recoil onto the pulley. As a result, the engine won’t start. Many recoil springs can be replaced individually, but it may be easier to replace the whole recoil starter assembly.

Parts
Recoil Starter for your John Deere Replacement PartLawn Mower
Recoil Starter - Part # 1646781 Mfg Part # 791363
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Cause 11Pre-Cleaner

If the lawn mower engine is hard to start the air filter pre cleaner might be clogged. This is rare. Remove the pre cleaner and clean it thoroughly.

Parts
Pre-Cleaner for your John Deere Replacement PartLawn Mower
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