Troubleshooting A Snowblower That Won’t Start

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You’d really rather not go searching for that old snow shovel buried behind the sports equipment at the back of the garage. However, you need something to tackle the six inches of accumulation that last night’s snowstorm deposited and your gas-powered snowblower simply won’t start.

Yes, yes – you know all about how doing a little preventative maintenance could have helped you avoid this predicament. But that was then and this is now. How can get your snowblower started and save yourself some lower back pain? Repair Clinic recommends fixing yourself some hot chocolate and then doing a little troubleshooting.

What it takes to make a gas-powered snowblower run

The first step to successfully troubleshoot an equipment problem is to understand how that equipment works. So, what does it take to make a gas-powered snowblower run?

Single-stage or dual-stage

Most gas-powered snowblowers, or snow throwers if you prefer, are classified as either single-stage or dual-stage. What’s the difference? Single-stage models will just use the auger to do all the work. The auger blades will collect the snow and throw that snow out of the chute in one motion.  Dual-stage snowblowers will use the auger to collect the snow and a separate impeller to throw it. Does this give dual-stage snowblower models an edge over single-stage ones? You bet. While single-stage snow throwers can handle snow up to six inches deep, dual-stage models can handle snow up to one foot deep or more, depending on the size of the auger housing.

The engine is the heart of every gas-powered snowblower

Whether your snow thrower is single-stage or dual-stage, the power that drives the auger and impeller is the engine, the heart of every gas-powered snowblower. Most single-stage and dual-stage models use a four-cycle engine. Similar to an automobile engine, four-cycle engines run on gasoline and have a separate sump for oil.

To start the engine, an ignition key must be inserted or turned into position. While larger engines often have an electric start feature that will allow the engine to be turned over by using the key or pressing a start button, smaller engines will require you to pull a starter rope to turn the engine over.

How the engine ignition process begins

When the starter rope is pulled or the electric start feature is activated, the starter engages a drive cup attached to a flywheel which rotates the engine’s crankshaft. The crankshaft connects to a piston which moves up and down within a cylinder as the crankshaft is turned. The rotation of the flywheel and the linear movement of the piston is what begins the ignition process. The flywheel has permanent magnets built into it and as it rotates past an ignition coil a magnetic field is created. This magnetic field induces electricity allowing the ignition coil to send voltage to a spark plug.

The four strokes of a four-cycle engine

Just as that magnetic field is being generated by the rotating flywheel, an intake valve opens on the engine as the piston travels down the cylinder, creating a vacuum that draws fuel and air through the engine’s carburetor where the two mix before entering the cylinder. This action is called the intake stroke of the engine.

Next, the compression stroke occurs as the intake valve closes and the piston travels back up to the top of the cylinder. The spark plug, having received voltage from the ignition coil, now fires and ignites the fuel and air mixture which pushes the piston back down the cylinder in what is known as the power stroke of the engine.

The momentum of the spinning flywheel provides enough force to drive the piston back up the cylinder. As this happens, an exhaust valve opens and the combustion gases exit through the muffler in what is called the exhaust stroke. The snowblower engine will continue to run and repeat these four cycles until it is shut off.

The 4 likely reasons why your gas-powered snowblower won’t start

Repair Clinic believes there are four likely reasons why your gas-powered snowblower won’t start, and, yes, all four are related to the engine:

  1. Defective spark plug – Due to carbon build-up and a weakened electrode, the spark plug will degrade over time which can prevent the snow thrower’s engine from starting. You should first inspect the spark plug for any damage or wear. If the spark plug appears corroded, you can be pretty sure the component is not operating at its best. You can also use an ignition tester to help determine if the spark plug is defective. As a general rule, it’s a good idea to replace an old spark plug with a new one once a year.
  2. Restricted carburetor – Given enough time, certain ingredients in the fuel used to run the snowblower can evaporate, leaving behind a thick, sticky residue. This residue can create a restriction in the carburetor which can stop new fuel and air from entering the engine. You should first try cleaning out the carburetor ports with carburetor cleaner to eliminate any clogs. If cleaning is not effective, you can often purchase a carburetor repair kit to replace some of the components or you can install a new carburetor altogether.
  3. Broken flywheel key – The flywheel key is a small metal piece fitted into a slot in the crankshaft so the crankshaft can successfully engage the flywheel. If the engine stops suddenly due to the snowblower hitting a hard object, the flywheel key is designed to break in half to prevent damage to the engine. However, the broken flywheel key will need to be replaced with a new one before the engine can be restarted.
  4. Malfunctioning ignition coil – Since the ignition coil is designed to send voltage to the spark plug while the engine is running, a malfunctioning ignition coil can cause the engine not to start. You should first use the ignition tester to confirm that the spark plug is working properly. If the spark plug is in good condition, you can use the same ignition tester to help determine if the ignition coil has failed.

DIY repair resources available all year round

Looking for a video to show you how to replace the carburetor on the engine powering the Toro Model 38752 Snowblower? How about the correct way to install a new ignition coil on a Cub Cadet snow thrower (model 31AM63TR756/2012)? Just visit the “Videos & Articles” section of Repair and discover free DIY repair resources, including thousands of procedural videos, step-by-step guides, and schematics, to keep your outdoor power equipment running great all year round.

Repair Clinic recommends using genuine OEM snowblower parts

Repair Clinic is also where you’ll find all the parts you need to fix your outdoor power equipment, home appliances, and heating and cooling systems. If you need a new spark plug, ignition coil, carburetor, or flywheel key to repair your snowblower, Repair Clinic recommends using only genuine OEM parts. That’s why Repair Clinic stocks original manufacturer parts, not knock-offs, that match snowblowers manufactured by such top industry names as Craftsman, Toro, Ariens, Honda, MTD, Troy-bilt, and Cub Cadet.

To find the right part for your snowblower, enter the equipment’s full model number into Repair Clinic’s “Search Parts Online & Get Answers”  search bar. What you’ll see is a comprehensive list of compatible parts for your model. You can then use the “Part Category” and “Part Title” navigation filters to refine that list to locate the exact part you need. Whether you’re a professional repair technician or an avid do-it-yourselfer, you’ve got a repair partner in Repair Clinic.  

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