Why Won’t My Snow Blower / Lawnmower Idle At One Speed?

If your lawn mower or snow blower refuses to have a smooth constant idle speed and tends to repeatedly speed up then slow down – you have what is known as a “ Hunting and Surging” idle. This is a common occurrence with snow blowers and lawnmowers. With snow blowers this is usually because they sit all summer long stored in some hot garden shed with old gas still in their carburetor and fuel tanks. With time, the gasoline fuel will start to break down leaving a residue that can plug the small fuel circuits in a carburetor. With lawn mowers the “ Hunting and Surging” idle is usually caused by dirt getting into the carburetor as these engines operate in a much dustier environment. However, you can have the same issue if your lawn mower has bee sitting all winter with unconditioned gasoline in its tank and carburetor too!

There are 2 main fuel circuits in a small engine carburetor – the Low speed fuel circuit and the High speed fuel circuit. When one of these fuel circuits becomes partially plugged the engine no longer receives a constant fuel flow. The fuel flow becomes variable which results in the engine idle speed ” Hunting and Surging”. The only thing to do is “get the dirt out” – and that means you will need to clean the carburetor!

When cleaning a carburetor I always try to use something like “Mechanic In A Bottle” first. Just add a cap full to a tank of fuel and let the engine run for 10 minutes. If the residue isn’t too bad you will actually hear the idle smooth out and the “Hunting and Surging” will stop.

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If this this does not work then you will need to remove the carburetor from the engine, disassemble it and then allow it to fully soak in “Carburetor Cleaner” for a night. The next day you will need to replace the internal carburetor parts with new parts from an appropriate Carburetor Rebuild Kit.

 

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Okay, now that you have done all this work and finally got your carburetor clean and engine running with a smooth idle – you can prevent this issue from happening again next season by using a FUEL STABLIZER additive. Simply add the recommended amount to your gasoline and your small engine should start first pull next season!

Hope this helps !

Larry Laser

Why do I need shear pins – can’t I just use a regular bolt in my snow blower?

Yikes! Never use a regular bolt to replace a “shear pin” bolt!

Some shear pin bolts look a lot like regular bolts while others look similar but with “relief” cuts recessed in their shanks or are fitted with special spacer collars.

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The main fundamental difference in the design of a shear pin bolt to that of a regular bolt is that a shear pin bolt is design to fail. That’s right! As weird as that may sound, shear pin bolts are designed to fail (shear off) at a specific level of shearing (sideways) force. It is with the failure of the shear pin bolt that potential damage is not extended to your snow blower drive train system. The shearing of the shear pin bolt releases all force off the snow auger allowing it to no longer be driven but to spin freely. The blower drive train still continues to spin but with a sheared pin the snow auger no longer turns. The brass driven gear is damaged because the use of a regular bolt allowed the full force of a stuck snow auger (caused by a rock that got caught between the auger and the lower snow scraper bar) to transfer back to the brass driven gear causing gear tooth breakage and other damage. Unfortunately I have had to replace a few expensive brass driven gears that were damaged beyond repair because the owner used a bolt instead of a shear pin!

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Using the correct shear pin bolt will only cost you a few dollars but this little special bolt was designed to save you having to spend much more on repairs!

How do I get my Snow Blower ready for the winter season?

Getting the snow blower ready for the winter season is never fun! It reminds us of what’s to come, but on the lighter side it’s better to get it ready before snow flies then after!

 

As I have said in earlier small engine blog posts, getting the gas out at the end of the season is a must. Failing to do so will only make the task of getting your snow blower running when you need it both harder and possibly much more expensive! I have seen carburetors that have been totally destroyed by old gas, and that means just more money if you want to put the machine back in service. If you have removed the gas then it’s just a matter of giving the snow blower a once over and or a quick tune up.

 

At the start of each season you should change the oil (use a good quality oil 5w-30) , change the spark plug , take the bottom cover off your snow blower and check all belts and shaft bearings. Also check the main drive friction disk – make sure it is in good condition (clean, no cracks). Be sure to lubricate all moving parts BUT DO NOT LUBRICATE THE FRICTION DISK PLATE! Any lubricant on the friction disk will reduce friction and cause your drive system to fail. Both the friction disk and the rubber edged drive disk should be clean and oil free. If you need to remove any dirt or oil from the friction disk use rubbing alcohol and a clean rag. Once you have ensured all moving parts that should be lubed have been lubricated, be sure to give each belt a close visual examination and replace any belt that is frayed or cracked.

 

Snow blowers are a little more involved than a lawnmower as they operate in an extreme wet / cold environment. Lots of lubricant is a must as this will prevent your pulleys from ceasing up. However, make sure you lube ONLY the centre pulley bearing area and not the pulley belt surface itself as you do not want to get any lubricant on a drive or blower belt!

 

By doing this every season you will provide years of trouble free operation with your snow blower.

 

Happy Snow blowing!

 

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