sounds like missing on new snow blower

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drifter420

Joined
Jul 8, 2004
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Ontario, Canada
So I got a yard machine MTD 10.5 Tecumseh snow blower brand new, and used it today.. and it sounded like it was missing all the time randomly ( like every so often every 5 seconds or abouts )with and without load.. is this normal? Is it from the governor? Or should I look at exchanging the unit?

Its been run for less then the 2 hours so I haven't changed the orginial oil yet( yes I checked for oil first before starting it )
 
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The 3 newer MTD snowblowers in my family with tecumsehs larger than 8hp (two 9's and one 10.5)all let off an off-beat pop hear and there. I'd think as long as you are not puffing black smoke or loosing power they are fine. This is one of the reasons I prefer OHV tecumsehs. They run smoother that the flatheads.

Joel
 
OK.. phew.. I thought it was a sign that it was going to self destruct.. and gettin the outlaw to drag it back to the store for me would've been a PITA

( but something I would definitely do if its called for )
 
You may need to tweak the carb settings (assuming it isn't a fixed EPA carb). You may be a little rich or lean. Have you observed black smoke when throttling up or when it misses slightly? This would indicate a rich condition.
 
I wasn't able to observe any ( but I was also plowing at night ) I will hopefully have a chance during the day sometime to check it
 
Newer engines are jetted on the lean side because of emissions. Sad to say, but that behavior can almost be considered "normal".
IF you can get gasoline without alcohol, that might help a SLIGHT amount.
 
Wow.. I wonder if there is a needle I can adjust for that or are they fixed jets? ( which means I'll have to change the carb.. which means I won't do it till the 4 year warrenty is up )

I looked up the manual and the only info regarding the carb was that if it needs adjustments.. it has be to sent in
 
I use Avgas in my mowers. It fixes this problem. It is a true gaasoline, without alcohol or ethanol in it. So, at least in my area, it runs a bit richer than pump gas.

Remember that pump gas may in effect, cause a carbureted engine to operate a tick on the lean side due to the makeup of the gasoline and the EPA regs.

Chris
 
Is the 10.5hp engine on your MTD the same as the "Sno-King" engine found on the Ariens blowers?

Dad has a 11528 Ariens DLE (11.5hp Tecumseh Sno-King engine, 28" path) with the aluminuim front diff. I don't have it nearby anymore so I can't check ... but I thought it was an OHV motor.

That one runs really strong. No missing that I can tell/remember ... but can be very hard to start without the electric starter.

The newish 12.5hp Briggs he has on his Tractor & Supply "Husky" wood splitter is a different matter ... it misses constantly as it turning the hydraulic pump (light load, I guess). It's a bit difficult to start but runs without quitting, especially when under heavier load.
 
Its marked as "Sno King". I don't think it's the same.. but it's rated at 10.5 not 11.5

I wonder what the difference between those 2 motors are
 
Originally Posted By: drifter420
Its marked as "Sno King". I don't think it's the same.. but it's rated at 10.5 not 11.5

I wonder what the difference between those 2 motors are


The 11.5hp is an over-head valve engine and the 10.5 is a side-valve/flat head. You'll see a valve cover and larger muffler on the OHV engine.

Joel
 
I have the same problem with a 2 year old Sears 26" with a 9HP Tec that I purchased used this past Spring. It was so bad I had to run it with partial choke all the time. Constant high speed popping with the choke off and no load. But what's curious is that under load and with partial choke it would never miss. And I discovered that when the fuel tank was down to a quarter the engine would run worse.

My son just purchased a brand new MTD with the same engine. His would run for about a minute and then quit. He discovered quite by accident that if the fuel cap was OFF the engine would run fine. He concluded that the fuel cap was the culprit. It has no vent to atmosphere so the vacuum it created was starving the engine for fuel. He drilled a small hole in the fuel cap and it solved the problem.

So today I examined the fuel cap on mine. Yep, no vent to atmosphere. Under the cap is a round metal disc attached to a rod. This rod is attached to a circular rubber diaphragm that also forms a seal between the cap and the tank. If you push the metal disc to the side slightly you can see two small vent holes with mesh. This is supposedly the vent but how it works when the cap is sealed is beyond me. So I decided to perform the same minor surgery my son did. I drilled a 3/32" hole just off center and taking care not to puncture the rubber diaphragm underneath.

The result? A world of difference. No more high speed miss with no load. And it even runs with the choke off.
 
Wow... I wonder if the gas cap would be my problem also.

How did you prevent the snow and water to get into the tank with a hole being exposed to the element?
 
Originally Posted By: drifter420
Wow... I wonder if the gas cap would be my problem also.

How did you prevent the snow and water to get into the tank with a hole being exposed to the element?



The hole is small enough so it does not appear to be an issue.
 
I drilled the hole in my gas cap small enough to just fit the plastic spray tube from my WD-40 bottle. Works great. Snorkel!
 
I have the same problem currently.
Mechanic says it's likely the carberator.
There are a couple of small jets/orficies that control
mid-range running(no load).
Engine will idle, and run OK when loaded, but even at WOT and no-
load those small openings get plugged and cause the surging.
Shouldn't happen on a new unit though.
He will fix next week.
Could also be the ignition module.
 
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