Snowblower Stalls When Auger Engaged

It's frustrating using kit that's just not up to the job. Snowblowers have it tough, but do they really? They only work a few months of the year, not a bad gig and that is the root cause of your problem.

A dirty carburetor is the most common cause of a stalling snowblower engine when the auger is engaged. Cleaning the carburetor and fresh gas will fix the stalling.

In this post you'll learn why your snowblower stalls when the auger is applied. You'll learn how you can fix it today and how to prevent this happening again.

Mower gas cap

Vented Gas Cap

Engine stalling

The root cause is as you now know, most likely a dirty carburetor. Tiny fuel passages inside your carburetor become clogged and restricts gas flow.

 

When the auger is engaged, the engine demands more fuel, when the carburetor can't supply it, the engine simply stalls.

This condition is known as fuel starvation.

Auger Brake

Although a fueling issue is the most likely cause, it's not the only possible cause.

A fault with the auger brake assembly may also cause the engine to stall when the auger is engaged. It is however the less likely cause and so we'll look at it towards the end of this post.

 

First we'll look at the fueling system.

Why does fuel starvation cause the engine to stall?

For an engine to run without stalling it needs a mix of air (oxygen) to gas ration of 14.7:1

 

It's known as the AFR (Air Fuel Ratio). It means for every 14.7 parts air the engine receives, it must also receive 1 part gas.

If either of these measurements are off, the engine protests by not running at all or poorly.

If the engine doesn't get enough gas in the mix, it's said to be running lean.

 

If on the other hand, the engine isn't getting enough oxygen, it's said to be running rich.

In our case, we suspect we a have fuel starvation issue, (lean) evidenced by the stalling engine precisely when more gas is needed (auger engaged).

What causes a lean condition?

It should be noted that a lean condition and fuel starvation aren't quite the same thing. A lean condition as you know means there's isn't enough gas in the mix.

The most common cause of a lean condition is a dirty carburetor, but there are many other root causes of a lean condition.

Here’s a list of the more common causes of a lean condition:

  • Fuel starvation (blockage)
  • Faulty carburetor
  • Fuel mix screw out of adjustment
  • Bad gas
  • E15 gas
  • Gasket leaks
  • Engine wear
  • Valve seating issue

Common fuel starvation causes

The good life may well be the root cause of your snowblowers stalling issue. When snowblowers retire at the end of the season, the gas in the fuel system starts to degrade.

Some owners drain the gas tank, however it's the gas in the carburetor bowl that's the problem. The ethanol fuel blend we all use today begins to degrade after just a month.

And degraded gas is the most likely cause of fuel starvation.

Components most likely affected, include:

  • Carburetor
  • Gas filter
  • Gas tank Faulty
Vented mower gas caps

Vented gas caps

Carburetor Diagnosis

Diagnosis is pretty simple, remove the carburetor bowl and check the contents. Finding a gungy deposit, corrosion or dirt means we found our problem.

The process looks like this:

  • Locate the carburetor
  • Turn gas tap off (or pinch gas line)
  • Place rags under the bowl
  • Remove bowl fastener

Try cleaning the bowl 

In some cases cleaning the carburetor bowl and fuel jet will solve the issue. It's worth a try, as cleaning the bowl and jet is a ton less labor than removing the carburetor to clean.

After refitting the bowl, check for leaks, older carb bowl seals and bowl fastener gaskets often leak after removal. If they do leak, replace the gaskets.

Snowblower Carburetor Cleaning

Cleaning the carburetor thoroughly means removing it. It is possible to spray carb cleaner into he carb but it's like shooting in the dark.

Removal, stripping, cleaning, rebuilding and refitting is the best solution. However, as said it is worth cleaning just the bowl and bowl fastener (jet type) before embarking on a carb teardown.

Snowblower Carburetor Removal

Small engines are easy to work on, for most task just basic tools are needed. That's true for this task. If you need tools, check out the "Snowblower maintenance tools page". 

Tools & products you’ll need, include:

  • Pliers Fuel clamp
  • Ratchet & socket set
  • Screwdriver set
  • Wire brush
  • Syphon
  • Carburetor cleaner
  • Gas stabilizer

 You'll find all these tools & products here on the "Snowblower maintenance tools page". 

The removal process is as follows:

  • Turn gas off or pinch gas line with clamp
  • Remove intake housing
  • Remove gas line
  • Take picture record of choke & throttle linkage locations
  • Remove carb fasteners
  • Take a picture record of gasket locations and orientations
  • Turn carburetor to ease choke and governor linkage removal
  • Move carburetor to a clean bench

Snowblower Carburetor Teardown

The teardown process is as follows:

  • Have container handy for small loose components
  • Remove gas bowl
  • Remove float and valve
  • Remove jet & emulsion tube
  • Remove idle jet (if applicable)
  • Remove fuel mix screw (if applicable) Count turns to remove

Carb Cleaning

To nail this task you'll need carb cleaner or better an Ultrasonic bath. 

The cleaning process is as follows:

  • Using carb cleaner and its straw, spray all passages of the carburetor
  • Using a wire brush strand, clean the port holes of the main & idle jet and the emulsion tube

Snowblower Carburetor Rebuild & Fit

Rebuild in reverse order, not the following tips when rebuilding and refitting:

  • When refitting the fuel mix screw, ensure to fit to the same number of turns (if applicable)
  • Drain the gas tank before fitting the carburetor
  • Ensure all carburetor gaskets are located correctly including their orientation (gasket leaks will cause engine surging)
  • Careful not to overtighten carburetor fasteners
  • Consider fitting new float needle, gas bowl seal, bowl fastener gasket and gas filter
  • Careful not to overtighten gas bowl
  • Fit choke and throttle linkages to the carburetor before fitting carburetor to the engine

Adding Gas Stabilizer

To prevent this problem in the future we have two options. One: We can drain all the gas from the machine including the gas bowl and fuel lines, or Two: We can add a gas stabilizer that will keep the gas fresh and protect the fuel system from gumming.

The gas stabilizer is mess free and a lot less work. Gas stabilizer is a chemical additive we add to the gas tank to keep the ethanol from going stale or eroding the plastic and rubber components of the fuel system.

You can check out the stabilizer I use here on the "Snowblower maintenance tools page".

Add stabilizer as follows:

  • Add gas stabilizer to a clean fuel can. Typically add 1/2oz. (tablespoon full) to a gallon of gas
  • Shake the can
  • Fill a low or empty snowblower gas tank to the top.
  • Run the engine for five minutes

Told you it was easy!

Auger Brake Assembly

The auger is fitted with a brake to stop it quickly when the handle bar auger lever is released.  

The system is simple, a spring loaded arm with brake block attached is pushed against the auger pulley, slowing it down and stopping it when the auger lever is released.

A brake is activated by way of cable from the auger lever.  

As you can imagine if the auger brake isn't releasing then the engine would naturally stall. This isn't a common problem, but should be eliminated as a possible cause. 

The system is simple, a spring loaded arm with brake block attached is pushed against the auger pulley, slowing it down and stopping it when the auger lever is released.

A brake is activated by way of cable from the auger lever.  

Checking the brake as follows:

  • Remove plug wire (twist and pull)
  • Turn gas off (if fitted)
  • Place plastic sheet over gas  tank neck and refit gas cap (prevents spill)Turn blower up and on to bin (auger housing)
  • Remove belly pan
  • Have helper activate the auger lever while you check auger brake clearance
  • Adjust if necessary 

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Auto Technician and Writer at Lawnmowerfixed | Website

John Cunningham is an Automotive Technician and writer on Lawnmowerfixed.com. I've been a mechanic for over twenty years, I use my knowledge and experience to write "How to" articles that help fellow gear-heads with all aspects of mechanical repairs, from lawn mowers to classic cars.