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Snow Blower Won’t Start (Mechanics hacks)

By: Author John Cunningham. Published: 2022/09/09 at 11:31 am

Moving snow is tough; we only realize just how tough it is when the blower breaks down and we are reunited with our trusty snow shovel. But for most folks, moving snow old school isn’t an option; I’m a mechanic, and I’ll bet we can fix your snow blower right now.

The number one common cause of snow blower no start is bad gas, but there are other possible causes; they include:

  • Carburetor issue
  • Spark plug issue
  • Ignition coil issue
  • Broken cable
  • Flat battery
  • Loose battery terminals
  • Faulty starter solenoid
  • Faulty starter motor
  • Stuck valve

In this post, you’ll learn about common snowblower no-start causes, how to diagnose them, and how to fix them.

Syphon old gas

It is worth pointing out early in the game – A snowblower that doesn’t start after sitting idle over the summer months likely suffers from stale gas or a fouled plug.

Draining the gas tank, refilling it with fresh gas, and cleaning the spark plug are two common fixes.

If that sounds like a fair description of your situation, you can jump on down to the fuel system diagnosis; and Spark plug check.

Here are some other common symptoms of a no-start snowblower, some of which may be a more detailed description of your snowblowers symptoms:

If none of these sound familiar, no problem. This post has you covered; keep reading.


Starting a Snow Blower

I know you know how to start a snow blower; you’ve been doing it for years, but for all the folks who may be new to the chore, here’s the detail on starting your snow blower.

First off, it might be helpful to know that all engines struggle to start in colder temperatures, and the reason is simple: colder temperatures mean the air is denser – denser, meaning there is more oxygen in the air.

And you’ll see why that’s a problem when you understand why oxygen levels are essential to starting an engine.

Gas engines don’t run on gas alone; they require oxygen also, but they need an exact ratio of one to the other for your machine to start and run at its best.


The sweet spot is 14.7 to 1. (14.7 parts oxygen to 1 part fuel); this ratio is known as the AFR or Air Fuel Ratio.

And it’s your carburetor’s job to ensure this ratio is correct. Your carburetor is a precision instrument, and it’s been factory-tuned to measure and mix air to fuel to a precise proportion.

Need more info on the fuel system, carburetor components, and how they work, you can check them out here.

Small engine carburetor components

If the proportion of air to fuel changes, you’ll know about it quickly. Your engine will either fail to start, stall or struggle to move snow.

A gas engine is said to be running in one of these three states:

Air to fuel ratio
  1. Running lean 18:1 – Too much oxygen/not enough gas in the mix.
  2. Stoichiometric – Just right 14.7 to 1.
  3. Running rich 12:1 – Not enough oxygen/too much gas in the mix.

The most common condition associated with cold starting is a lean condition. Meaning there isn’t enough fuel in the mix.

Choke on

To combat this, snowblowers have two cold start features – the choke and the fuel primer. We’ll cover them in more detail below.


All snowblowers are fitted with a choke. A choke is a control lever or knob used to activate a choke plate. When engaged, the plate chokes off or limits the air supply and, at the same time, increases fuel to the engine.


The effect creates a richer condition, the perfect fuel mix for starting a cold engine.

Primer bulb

Snowblower will have both a choke and a primer bulb. Operating the rubber bulb causes fuel to squirt directly into the carburetor’s throat. This reduces the crank time to start a cold engine. You’ll still need to operate the choke lever, as an engine will need some choke until it heats up.

Primer bulb

The primer bulbs’ main function is to aid the initial start procedure.

Starting a Snow Blower From Cold

When starting a snowblower from cold in cold weather conditions, we’ll need to richen the fuel mixture and to do we’ll use the choke control lever and also a primer bulb if fitted.

The process is as follows:

It’s great practice to check the oil level and give your machine a quick visual, looking for any loose or damaged components.

Snow blower Starting sequence
  1. Turn ignition On
  2. Turn gas tap On
  3. Set throttle to full (if separate control)
  4. Set choke to full
  5. Press the primer bulb 3 to 4 times
  6. Pull start, or use the start button or plug-in electric cord

After it starts, move the choke back to the 3/4 to 1/2 position, and when the engine is warm, turn the choke off altogether. Running a warm engine with the choke On full will cause sputtering.

I wrote a post about snowblower choke use, and you can check it out here.

Starting a Snow Blower From Hot

Starting a warm engine is a ton easier. That said, you’ll likely still need to use a little choke, but usually no need to add the additional primer shot of gas.

Basic Snow Blower No-Start Checks

In this section, we’ll check all those often overlooked, easy-to-fix solutions for a no-start. It makes sense to check these first that way; we could save ourselves a ton of time and effort.

Here’s the checklist in order of commonality:

  • Fuel valve turned On
  • Fuel in the gas tank
  • Ignition set to On
  • Plug wire On OK
  • Follow the correct start procedure (covered above)

What’s a Fuel/Gas Valve?

Some folks may not be familiar with a fuel valve. All snowblowers are fitted with a gas tap (also known as a fuel valve or tap). Its function is to prevent gas flow from the gas tank to the carburetor. It’s designed to be used when the machine is not in use and is very helpful when running carburetor tests, maintenance, and repairs.

Snow blower Gas off

A simple valve typically turns perpendicular to the gas line when the flow is blocked and in line with the fuel hose when the fuel is flowing.

Okay, that’s all the easy stuff out of the way, and if none of the above helped, we’ll need to roll our sleeves and dig deeper.

No-Start Snow Blower Symptoms

An engine needs three ingredients to start and run; it needs a good:

  1. Ignition system
  2. Fuel system
  3. Compression system

A no-start fault means there’s a fault with one of these systems, but which one?

A common diagnosis approach is to gather all available information that may help indicate which system has failed. The type of symptoms your machine exhibits usually offers the very best clues. I’ve included a table of common symptoms below.

Sometimes, symptoms don’t narrow down the field, and sometimes, symptoms point to a possible failure in two or all three systems, which isn’t helpful.

In such instances, we are left with a top-down approach to our diagnosis. A top-down approach typically involves testing each system systematically, which can be time-consuming. We won’t be doing that; I have a mechanic’s hack to share, which we’ll get to shortly.

First, it should be noted that different snowblower starting systems affect diagnosis: types include the pull cord, the Battery and starter, and the electric cord. I covered them below in more detail, including common symptoms and causes.

But if you want to jump ahead to the mechanic’s hack, here is the link – Gas shot test

What type of starting system?

While snowblower engine symptoms and diagnosis are largely the same, the range of starting systems fitted are completely different, as is the diagnosis procedure.

Typically, there are three different starting system types:

Each starting system offers its own set of symptoms, and now, we’ll take a look at each of them in turn.

Pull cord starting system description & symptoms

A pull starter is the basic starter type, and many electric start snowblowers are also fitted with a pull cord starter. Pull cords do give issues, but they are generally pretty obvious. Anyhow, here’s a list of pull cord symptoms together with internal site links to the fix:

SymptomPossible Issues
Pull cord hard to pullEngine oil over full; Hydro-locked engine; Crankshaft obstruction; Drive belt engaged; Auger engaged.
Pull cord catches but won’t turn over the engineEngine seized; Hydro-locked engine; Crankshaft obstruction; Drive belt engaged; Auger engaged
Pull cord won’t catchPull assembly pawls worn out
Pull cord won’t retractPull recoil spring broken
Pull cord snaps backPossible broken shear key

Check out this video; it covers common pull cord issues “Pull cord common faults video.”

Battery & starter system description & symptoms

This system includes an onboard battery, solenoid, starter motor, and starter switch.

SymptomsPossible Issues
Engine turns over slowlyLoose/dirty battery terminals; Faulty/flat battery; Too much oil; Auger engaged; Drive engaged
Engine just clicksFaulty solenoid; Flat/faulty battery; Compression release issue; Valve lash issue
Engine clicks repeatedlyFaulty/flat battery; Loose/dirty battery terminals
The engine won’t crank over -no soundFaulty/flat battery; Loose/dirty battery terminals; Blown fuse; Ignition wiring issue

Electric cord starter system description & symptoms

This system includes a starter motor and starter cord, which sends power to the starter motor when plugged into the household power supply.

SymptomsPossible Issues
The engine won’t crank overCord issue; Household power supply issue; Starter motor issue
Engine turns over slowlyDamaged cord; Faulty starter motor

Diagnosing a No-Start Snow Blower

You’ve looked at the common snowblower no-start symptoms, and they didn’t help any, and now let’s try the top-down diagnosis approach. As promised, I’ll show you a mechanic’s hack to short-circuit the laborious task of systematically testing each of our three systems.

Gas Shot

This test is an elimination round, and to nail it successfully, we’ll need the following tools and supplies:

  • Plug spanner
  • Funnel
  • Fresh gas

The mechanics gas shot hack is as follows:

Gas shot
  • Remove the spark plug
  • Use the funnel to help add a cap full of fresh gas to the cylinder
  • Refit the spark plug
  • Attempt to start the engine

If you need more help, you’ll find a gas shot video here.

Two outcomes are likely:

1 The engine started or attempted to start – If this sounds like you, you likely have a fueling issue; go ahead and jump to fuel system repairs here.

Plug cleaning

2 The engine did not attempt to start – If this sounds like you, you may have a compression system issue. However, an ignition system issue is far more likely, so best to start by checking for spark.

1 Ignition System

The ignition system has two important jobs, they are:

  1. Create a strong spark
  2. Deliver spark at just the right time

Get either of these important jobs wrong, and the magic won’t happen. Below is a list of the ignition components, a brief description of their function, and internal links to the diagnosis process.

The ignition system consists of the following components:

  • Spark plug – Causes the voltage to jump the plug gap creating the all-important spark.
  • Coil wire – Transports the voltage from the coil to the plug.
  • Coil/armature – Creates the voltage needed to fire the plug.
  • Flywheel – Rotating flywheel magnet excites the coil generating a voltage.
  • On/Off ground switch – Removes or applies ground to the coil, which controls coil voltage.
  • Battery & starter/ pull cord – Turns over the engine over 400rpm to create a sufficient spark.

If you’d like to know more about how ignition systems work, check out the link below.

Symptoms – Typical ignition system fault symptoms include the following:

Ignition System SymptomsPossible Issue
No startFouled/faulty plug; Faulty coil; Weak battery/starter
No sparkFouled/faulty plug; Faulty coil
Starts & runs until hot, then stallsFaulty coil
Won’t start when hotFaulty coil
MisfiringFouled plug; Faulty coil; Wiring issue

Tools – To test the ignition system successfully, we’ll need an inline ignition system tester; you’ll find the one I recommend here on the “Small engine repair tools page.”

Diagnosis – When diagnosing the ignition system, our focus turns to the spark plug first, and for good reason. The plug is under the most stress and is the most likely failure point. But the plug is also really easy to access and check, so it makes sense to eliminate it early in the game.

Grounding spark plug

It is always worth having a spare plug handy for fast swap-out diagnosis; if not, cleaning and gapping the plug is often enough to restore operation.

The coil, also known as an armature, is the next most likely ignition component to fail, and we’ll cover testing below in the diagnosis section.

The links below will take you to a post or video where I’ve previously covered the repair. The post or video may be related to a lawnmower, but the process is identical.

The most common ignition system issues, diagnoses, and the fix are as follows:

Fouled spark plugCheck sparkClean & gap
Wrong spark plugCheck specFit correct plug
Faulty coilRun inline ignition testReplace coil
Faulty coil wire capRun inline ignition testReplace cap

I covered the whole process of testing the ignition system here in a video.

If your spark seems fine, go ahead and check your compression now.

2 Fuel System

Your fuel system is tasked with a few critical jobs, which include:

  • Store gas
  • Filter the gas
  • Move gas from tank to carburetor
  • Hold and maintain sufficient gas in the carburetor bowl
  • Meter and mix gas proportionally

Snowblower fuel systems cause a ton of trouble, and it’s not because they are faulty in some way; it’s because our gas is blended. Gas comes with a percentage of ethanol in it. This presents a problem for all small engines as their fuel systems are open to the atmosphere, and that causes blended gas to turn stale over the idle months.

Gas tank draining

I mention this early in the diagnosis as if your fueling system is causing issues; there is a good chance fuel contamination is to blame.

Below is a list of the fuel system components, a brief description of their function, and an internal link to the diagnosis.

Fueling system components;

  • Gas tank – Stores gas
  • Gas cap – Vented cap
  • Fuel lines – Gravity feeds gas from tank to carb
  • Gas tap – Controls flow of gas
  • Gas filter – Filters gas may be inline, or gas tank integrated
  • Carburetor – Mixes oxygen and gas and feeds the engine

Need more info on small engine fuel system, carburetor, how it works, and components, check it out here.

Symptoms – Typical fuelling symptoms include the following:

Fueling System SymptomsPossible Issue
No startBad gas; Dirty carb
Starts then diesDirty carb
SurgingDirty idle jet
Only runs on chokeDirty carb
Leaking gasWorn float needle
White smoke & high oil levelWorn float needle

Tools – We’ll need a selection of wrenches and some fresh gas. You’ll find all the fueling system tools I recommend here on the “Small engine repair tools page.”

Diagnosis – The gas shot test is the fast-track way to diagnose a fueling issue. Fueling issues, as you likely know, mostly revolve around stale gas. Blended gas is a problem for all small engine kit.

The links below will take you to a post or video where I’ve previously covered the repair. The post or video may be related to a lawnmower, but the process is identical.

The most common fueling issues, diagnoses, and the fix are as follows:

Diry fuel bowlInspect bowlClean bowl
Stale gasGas older than two monthsDrain tank & bowl
Blocked idle jetCheck idle jetClean idle jet
Dirty carbInspect carburetorClean carburetor
Worn float needleInspect needleReplace needle

I covered the whole process of testing the fueling system here in a video.

3 Compression

Small engine 4 stroke cycle

The first two ingredients of the internal combustion engine – spark and gas are easy to conceive, but compression, what is it anyway? And how is it important?

Compression squeezes the cylinder’s contents (oxygen & gas); the piston and rings push the cylinder’s contents into the much smaller space at the top of the cylinder, known as the combustion chamber.

Compressing the cylinder does three important things:

  1. Concentrates energy at the top of the cylinder where the spark plug lives
  2. Prepares the piston at the top of the cylinder, ready for the power stroke
  3. Heats the combustion chamber and fuel mix – perfect conditions for ignition

The compression system relies on the following components:

  • Piston rings – Rings seal the cylinder
  • Head gasket – Gasket seals the block and head interface
  • Valve seating – Valves open and close sequentially and create a seal when closed
  • Battery & starter/ pull cord – Turns over the engine over 400rpm to create sufficient compression

Symptoms – Typical poor compression symptoms include the following:

Compression System SymptomsPossible Issue
No startSticking valve
High oil consumptionWorn rings; Head gasket
Blue/white smokeWorn rings
Plug foulingWorn rings
MisfiringValve issue
Sound of leaking airHead gasket
Lean conditionVacuum leak
Hanging idleVacuum leak

Tools – To test compression, we’ll need a test kit; you can check the kit I recommend here on the Small engine repair tools page

Diagnosis – To create compression, the cylinder must remain sealed at critical stages of the engine cycle. Meaning if the engine leaks air, it won’t fire. Diagnosis, therefore, is mostly about making sure the engine doesn’t leak air.

Compression test

The links below will take you to a post or video where I’ve previously covered the repair. The post or video may be related to a lawnmower, but the process is identical.

The most common compression issues, diagnoses, and fixes are as follows:

Sticking valveInspect valveRelease valve
Head gasketCompression testReplace head gasket
Valve issueCheck valve lashAdjust valve lash
Vacuum leakCompression test
Worn ringsWet & dry compression test

I covered the whole process of checking compression here in a video.

Sum Up

A snowblower that doesn’t start after sitting idle over the summer months likely suffers from stale gas; draining the gas tank and carburetor bowl and refilling it with fresh gas fixes that problem. In addition, remove, clean, and check the spark plug gap or replace the spark plug.

You may also find the following posts helpful: