The 6 Reasons Why Your Gas Tiller Won’t Start

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Backyard enthusiasts know that having fertile soil is the essential component of a successful garden. If you’re serious about your green thumb, chances are you depend on a gasoline-powered tiller to cultivate that soil each year. Just like other outdoor power equipment, a tiller needs to be properly maintained in order for it to perform as expected. If your gas tiller has been stored away in a shed for several months, you may find that it runs rough or it may not start at all.

Why won’t the tiller engine start?

Home-use gasoline-powered tillers will either have a four-cycle engine, which has a separate sump for oil, or a two-cycle engine, which requires the gasoline to be mixed with the oil for the engine to operate properly. Attempting to run a two-cycle engine without a suitable oil and gas mix will cause the engine to seize due to insufficient lubrication. If you’re concerned about getting that gas/oil balance right, you can use a pre-mixed fuel and oil product like TRUFUEL 50:1 Mix to fill the tank.

So you’re confident that you’ve got the gas/oil mixed correctly, but the tiller engine still won’t start? Here are the six most likely reasons why:

  1. Defective spark plug – Due to carbon build-up or a weakened electrode, a spark plug will degrade over time and be unable to ignite the compressed fuel and air inside the engine’s combustion chamber to start or run the tiller engine. You can use an ignition tester to help determine the strength of the spark plug, but it’s probably easier to simply replace it with a new one, something we recommend doing annually.
  2. Restricted carburetor  –  Old or bad fuel can leave a gummy residue inside the carburetor creating a restriction. This will prevent the proper ratio of fuel and air from entering the cylinder which can cause the engine to have trouble starting. You should always make sure you keep fresh fuel in the tank and use a fuel stabilizer to help preserve its quality. As noted earlier, you can use a premixed fuel and oil product for better stability. You can try cleaning the carburetor ports with a dedicated carburetor cleaner, or WD-40, to clear out the restriction, but if the clog is particularly bad, you may need to purchase a new carburetor.
  3. Malfunctioning ignition coil – Since the ignition coil is designed to send voltage to the spark plug while the engine is running, the spark plug will not be able to ignite the fuel to keep the engine running if the ignition coil is malfunctioning. As with the spark plug, you can use an ignition tester to help determine if the coil has failed and requires replacement.
  4. Broken flywheel key – The flywheel key is a small metal piece that fits into a slot in the crankshaft and engages with the flywheel. It is designed to break if something obstructs the flywheel to prevent damage to the engine. Over time, the key may become worn and break on its own. In either case, the key will need to be replaced with a new one in order for the crankshaft to rotate the flywheel to start and run the engine.
  5. Malfunctioning recoil starter – The recoil starter may be malfunctioning and unable to engage with the engine crankshaft. While you can often replace individual components within the recoil assembly, such as the recoil pulley, rewind spring, or the starter rope, you can save yourself some time if you just replace the entire assembly.
  6. Faulty on/off switch – Many tiller models will have an on/off switch that will need to be set to the “on” position before the engine can be started. If the switch is faulty, it may prevent the engine from starting. To help determine if the switch is defective, you can use a multimeter to test the switch for electrical continuity – a continuous electrical path present in the part. If the switch tests negative for continuity, you’ll know the switch is bad and will need to be replaced.

Don’t forget to inspect other tiller components

In addition to the engine parts that need to be maintained, there are other components as well that can interfere with proper tiller operation:

  • Damaged tines – The tiller tines are the key component when tilling the soil, so if the tines appear damaged, extremely rusty, or bent, you should replace the old tines with new ones.
  • Frayed belt – If your tiller’s tines are belt-driven, be sure to inspect the belt for wear. A belt that hangs loose on the pulleys or one that is frayed should be replaced to ensure optimum performance when cultivating the soil.

Keep your tiller in prime condition with parts from Repair Clinic

Repair Clinic stocks all the parts you need to maintain or repair your tiller’s engine, such as spark plugs, carburetors, ignition coils, start switches, and recoil starters, as well as tiller components like tines and belts. For a complete list of parts that match your tiller, enter the tiller’s full model number in the Repair Clinic website search bar. You can then use the “Part Category” filter (“Starter”) and the “Part Title” filter (“Rewind Pulley and Spring”) to identify the specific part you need. Repair Clinic carries genuine OEM parts for all the top brands, including Craftsman, Echo, Homelite, Husqvarna, Lawn Boy, MTD, Mantis, Poulan Pro, Ryobi, Toro, and Troy-bilt, but you’ll want to make sure you’re purchasing the exact item that matches your tiller model. In addition to millions of replacement parts for outdoor power equipment, appliances, and heating and cooling products, Repair Clinic also has thousands of “how-to” videos, diagrams, and articles to help you do the repair quickly and successfully.

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