If your snow blower dies when under a load you have a problem.
If you only get light snowfalls, getting a shovel and clearing your drive of the white stuff isn’t too much of an issue.
But if you get a lot of snow you want a reliable snow blower to clear it quickly.
What you don’t want is a snow blower that immediately stalls or dies as soon as it encounters anything substantial.
So let’s take a look at the reasons why your snow blower could be dying when under load and how to fix them!
Why Does My Snow Blower Die Under Load?
If your snow blower is dying or stalling under load, generally it is because the engine is being starved of fuel. More often than not the main jet in the carburetor might be clogged or there could be a blockage elsewhere in the fuel system. Some quick checks you can make first though are the spark plug, gas cap and the quality of the fuel in the machine.
Reason #1: It Needs A New Spark Plug
The first place to check in the event of any mechanical issues is the spark plug.
A weak spark plug often isn’t enough of an issue to stop a snow blower from starting, but can cause it to stall or die as soon as it comes under any kind of load.
The color of the spark plug also gives you an indication of the health of the engine.
Replacing a spark plug is cheap and easy, and will often solve the problem.
Reason #2: The Gas Cap Isn’t Venting Properly
Another quick and easy check before you get to the serious stuff is the gas cap.
If the gas cap vents get plugged, a vacuum can build up in the tank that starves the engine of fuel, causing it to stall or die.
Try running it with the gas cap loose.
If it runs better then you know this is most likely the problem.
You can get a new gas cap or just drill holes into the existing one to help it run better.
Reason #3: The Gas is Old
One more quick check is the gas.
If the gas has been sitting in the tank for a while it will have turned stale, and possibly blocked the carburetor.
Drain the gas, add new gas and see how it runs then.
Reason #4: Something is Starving the Engine of Fuel
If your snow blower is continually dying or stalling as soon as it hits a heavy load, then something is starving the engine of fuel.
Trying running your snow blower with the choke half on and see how it responds.
If it performs better with the choke on, then the engine is starved of fuel, and this could be occurring anywhere in the fuel system, from the fuel tank to the fuel lines to the carburetor.
The color of the spark plugs is also an indicator of whether the engine is being starved of fuel, or running lean as it is also known.
A normal spark plug will have brown or grayish tan deposits on the side electrode.
If the tip of the insulator tip is blistered, the electrodes are melted or there are white deposits on your spark plug, then that could point to an engine that is running lean.
If your spark plug is another color entirely check out this spark plug color chart.
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Reason #5: The Carburetor is Blocked
So if your snow blower runs much better under load with the choke on, there is a strong possibility the problem could be the carburetor.
Remove the carburetor, and clean it thoroughly with carb cleaner.
Make sure you get in all the small parts and pay particular attention to the main jet.
More often than not, a lean running condition and stalling under load is down to a blocked main jet.
Clean that with carb cleaner and then give it a blow with compressed air, I always avoid poking wire into it as this could cause more damage.
Note that the main jet has two holes. One of which is very visible, but it is the second hole, which is a tiny pinhole that can often be responsible. Make sure you clean both thoroughly.
If the jet on the carburetor is adjustable, then simply opening it up will let more fuel in. You can do this whilst it is running, the screw is usually on the bottom of the carburetor float bowl.
Talking of the float bowl, there could also be debris in here, so make sure this is cleaned as well.
If the problem persists, you might need to rebuild or replace the carburetor.
Reason #6: The Fuel System is Blocked
If the carburetor looks good, then something else in the fuel system is causing the problem.
Check for a blockage in the fuel system.
The fuel line could be collapsed or clogged. Check the fuel filter, as that might need to be changed or at least blown through and cleaned.
Also take a look at fuel inlet valves and make sure they are dropping sufficiently to allow enough fuel into the fuel bowl.
Reason #7: Check the Exhaust Valve
Check the clearance on your exhaust valve.
If it is tight and not closing properly it means your snow blower won’t be reaching peak RPMs and then when you hit a big load of snow, it will stall or die.
If you are finding your snow blower shuts off when it is hot, that is because when the engine gets warmer it causes the valve stems to lengthen, decrease valve clearance and then not let the valve seal itself properly when it closes, causing a loss of power.
The video above explains how to check and adjust the valves.
Reason #8: There Is A Lack of Compression
A common result of the exhaust valve lengthening in the scenario above is poor compression.
Your snow blower will misfire, not start or stall or die under a load if it does start.
You can use a compression gauge to check compression levels.
Questionable compression from a pull start I would consider to be anything below 50 PSI, below 40 PSI and you definitely have a problem.
If it isn’t related to the exhaust valves, poor compression might be down to a blown head gasket or worn cylinders/piston rings.
Reason #9: Check the Piston Rings
Talking of piston rings, if they are stuck it will affect the performance of any small engine.
Try pouring some seafoam in the spark plug hole, pull it over slowly once, and then let it sit for several hours. This can often free up stuck rings and carboned-up valves.
Then try and start it again.
If it works change the oil and spark plug as they may have been diluted by the seafoam.
Reason #10: The Governor Is Faulty
The governor regulates the speed of the engine and stops it from over-revving.
It opens the throttle when the engine slows down to keep the RPMs at the correct range.
If the governor is not working correctly then it won’t be able to regulate the engine speed.
If the governor arm doesn’t move at all check the spring that connects the governor to the throttle and see if it is broken.
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Reason #11: The Flywheel Key Has Broken
The flywheel key fits into the crankshaft and engages the flywheel.
If it is broken or sheared, it could cause the timing to be off enough for it to start ok, but not to be able to run under load.
If it is broken a replacement is necessary.
Reason #12: The Auger Belt Might Be Slipping
If you pull the auger handle and the auger and impeller spin as you would expect, but when you drive into snow your snow blower will gradually throw the snow shorter and shorter distances until it stalls completely, then the auger belt could be slipping.
Check the belt, and see if it needs replacing or tightening
Reason #13: Check the Ignition Coil
The ignition coil sends voltage to the spark plug whilst the engine is running.
If it is defective or leaking current it will affect the engine, causing it to not start or stall or die.
Follow the spark plug wire from the plug to the coil and look for any leakage of current.
If your snow blower is dying or stalling under a load, then you should quickly check a few things, namely the spark plugs, gas cap and the gas itself.
If you can rule out any problems with them then it is likely something is starving the engine of fuel and there is a problem with the carburetor or elsewhere in the fuel system.
Outside of this, there are a few other possible causes as show in our infographic above.
But first of all try running your snow blower with some choke, if it performs better then this points to a problem with the carburetor. It is most possibly clogged and fuel is not able to get through properly.
More often than not this is the cause of a snow blower stalling or dying when under a load.