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Old 02-02-2011, 04:30 PM   #1
gtivr4
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Default Snowblower runs rough and stalls under load

OK, I am a complete newb when it comes to small engines, so bear with me.

I bought a 10hp 28" snowblower this fall. It has a Tecumseh engine. Every time I have used it, it has been surging up and down, and can only run at full throttle. And now today it has been acting up, it stalls after running for a minute or two, and won't restart without running the electric starter. I just pulled the carb, and rebuilt it. It doesn't have any real adjustments that I can find (just one that controls the throttle). I've done some searching and its seems to be that its running lean (there is also a bit of flame coming out the exhaust from time to time). Some say its a spark plug (replaced that), gunky carb (rebuilt that), the governor (haven't checked that yet), or a clogged fuel line/filter (haven't checked that either)

Where do I go from here? Obviously not the best day to have a busted snow blower, luckily I was able to clear the driveway once.
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Old 02-02-2011, 05:07 PM   #2
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Default Re: Snowblower runs rough and stalls under load

newer emissions carb with no adjustable mixture needles?

and what exactly did you do when you say you "rebuilt" the carb. For some that could just mean they opened it and wiped the bowl and put it back together.

A rebuilt carb to me means it took a bath in some parts cleaner for a few days, had new O-rings installed on the emulsion tube [emissions only], had its low and high idle jets replaced, and needle/seat replaced.

A red hot muffler with or without belching flame is definitely a sign of running lean.

Last edited by Skin; 02-02-2011 at 05:18 PM.
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Old 02-02-2011, 05:09 PM   #3
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Default Re: Snowblower runs rough and stalls under load

clogged main jet?
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Old 02-02-2011, 05:17 PM   #4
Tom2
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Default Re: Snowblower runs rough and stalls under load

I'd make sure the float isn't full of gas. If you have it out of the carb, shake it next to your ear to tell.

I've rebuilt a carb 3 times, not noticing the float had a super tiny pinhole in it.
Make sure to put a new needle in as well. Spray compressed air through all passages. Blow compressed air through the line and replace the filter. You can buy computer keyboard cleaner (compressed air in a can) in the electronic department at Wal-mart (if you don't have a compressor)

I'd make sure your 110% set on the carb before exploring other possible causes. Seems to be the issue 9 times out of 10 on small engines.

New ethanol blends are terrible for small engine carburetors.

Last edited by Tom2; 02-02-2011 at 05:21 PM.
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Old 02-02-2011, 05:21 PM   #5
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Default Re: Snowblower runs rough and stalls under load

if the float fills with fuel you'd know it right away as it will sink opening the needle valve and start pooring out of the air intake. You'd find a pool of gas on your floor. It would not cause a lean running issue or cause the machine to die as it would actually work WITH the running engine by keeping the carburetor bowl full of fuel just the same as a correctly functioning float.

Last edited by Skin; 02-02-2011 at 05:24 PM.
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Old 02-02-2011, 05:25 PM   #6
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Default Re: Snowblower runs rough and stalls under load

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if the float fills with fuel it will sink opening the needle valve and start pooring out of the air intake. It would not cause a lean running issue or cause the machine to die as it would actually work WITH the running engine by keeping the carburetor bowl full of fuel just the same as a correctly functioning float.
I agree that it wouldn't cause a lean condition, as he may have. But it's still something to check any time you have one of those carbs apart. It seems to be pretty common. Happened on 2 of my Tecumseh motors.
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Old 02-02-2011, 05:28 PM   #7
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Default Re: Snowblower runs rough and stalls under load

i've seen it once in 6 years and hundreds of machines . By all accounts its incredibly rare.

They actually stopped using brass floats some time ago. More recently they're molded plastic.

Like i said you'd notice it right away. Heavy float = puddle on your floor.
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Old 02-02-2011, 05:30 PM   #8
tvfd911
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Default Re: Snowblower runs rough and stalls under load

Hopefully it is your carb. My blower was doing very similar things, but it was caused by valves that were burned out and the cylinder being egged out, but that's what I got for spending $50 on a craigslist special. This winter I put a HF chinese knockoff 11hp engine on it and it is a whole new animal.
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Old 02-02-2011, 05:31 PM   #9
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Default Re: Snowblower runs rough and stalls under load

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i've seen it once in 6 years and hundreds of machines . By all accounts its incredibly rare.

They actually stopped using brass floats some time ago. More recently they're molded plastic.

Like i said you'd notice it right away. Heavy float = puddle on your floor.
Wow, really? Yes, it was brass both times. I don't think I've ever owned a small motor newer than the mid 80s

What surprised me the last time is I didn't notice the weight to it. And it wasn't dripping badly. Just a tiny, tiny pinhole that would fill up after running a few minutes and fill the oil with gas.
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Old 02-02-2011, 05:33 PM   #10
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Default Re: Snowblower runs rough and stalls under load

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Hopefully it is your carb. My blower was doing very similar things, but it was caused by valves that were burned out and the cylinder being egged out, but that's what I got for spending $50 on a craigslist special. This winter I put a HF chinese knockoff 11hp engine on it and it is a whole new animal.
i'd be worried about valves as well. I cut new stems and seats on a motor at least once a week, generally they're often newer. I thank the emission carbs for causing the engines to run hotter. As much as i've done it, it still boggles my mind that i'm doing something to an engine thats probably 8-10 years old while i hardly ever have to get into the 30-40 year old antiques. It seems to plague the 5-7hp engines a lot more than the 8-10s though.
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Old 02-02-2011, 06:53 PM   #11
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Default Re: Snowblower runs rough and stalls under load

Almost invariably, surging is caused by a fuel flow problem. Usually, the fuel flow problem is a clogged main jet and/or emulsifier. Totally disassemble the carb, soak for 30 minutes in carb cleaner, blow all the passageways with compressed air canned carb cleaner, and rebuild with new gaskets. Make sure all the pickup holes on the emulsifier near the bottom of the float bowl are totally cleaned and open. That's where Tec carbs have a lot of problems.
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Old 02-02-2011, 07:34 PM   #12
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Default Re: Snowblower runs rough and stalls under load

My buddy's Crapsman was doing something similar, stalling surging and basically running poorly. Found the fuel line pinched under the cowl where it bends coming from the fuel tank. Got some marine double walled fuel line and it solved the problem. Just my 2 cents.
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Old 02-02-2011, 08:16 PM   #13
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Default Re: Snowblower runs rough and stalls under load

I have a Toro from 1967, runs great. But over years of use, it runs best at an "Over Rich" state, without a load it starts to Load up a bit, but, under a load, it runs strong and never even stumbles.
Another good test was today...18" to 24" snow in Chicago. Did mine and my Neighbors place...4 tanks of Gas, but a Rich Running Toro is a Happy Toro!!!
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Old 02-02-2011, 09:08 PM   #14
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Default Re: Snowblower runs rough and stalls under load

Quote:
Originally Posted by KCarGuy View Post
I have a Toro from 1967, runs great. But over years of use, it runs best at an "Over Rich" state, without a load it starts to Load up a bit, but, under a load, it runs strong and never even stumbles.
Another good test was today...18" to 24" snow in Chicago. Did mine and my Neighbors place...4 tanks of Gas, but a Rich Running Toro is a Happy Toro!!!
Same here, but I have a WAY newer model, 1974.
Old stuff is good!!!!
They say we only got 12", but both our drives were 24+.

O.P. check the fuel line, some have a little plasitc screen inline.
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Last edited by hofferwood; 02-02-2011 at 09:11 PM.
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Old 02-02-2011, 10:55 PM   #15
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Default Re: Snowblower runs rough and stalls under load

Replace the throttle/governor springs. One should run from the throttle mount on the engine to the carb butterfly valve and the other runs from the carb butteryfly valve to the fan blade under the cowl. If you have no throttle controller then you may just have the single spring from the carb to the fan blade. Governor sets speed and as engine speed drops when under load the cooling air slows and the fan blade drops causing the throttle to open and speed up the motor. When those springs get old and worn they bounce around and you get the fast/slow/fast engine speed thing or sometimes they don't increase speed fast enough and the motor stalls.
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Old 02-02-2011, 11:58 PM   #16
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Default Re: Snowblower runs rough and stalls under load

I had troubles with my non-adjustable carb on my 9hp snowblower. $70.00 later I had the old style (new) adjustable carb and all the lean running problems went away.
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Old 02-03-2011, 01:35 AM   #17
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Default Re: Snowblower runs rough and stalls under load

Quote:
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Replace the throttle/governor springs. One should run from the throttle mount on the engine to the carb butterfly valve and the other runs from the carb butteryfly valve to the fan blade under the cowl. If you have no throttle controller then you may just have the single spring from the carb to the fan blade. Governor sets speed and as engine speed drops when under load the cooling air slows and the fan blade drops causing the throttle to open and speed up the motor. When those springs get old and worn they bounce around and you get the fast/slow/fast engine speed thing or sometimes they don't increase speed fast enough and the motor stalls.
Tecumseh Vertical shaft L Heads dont have a "fan blade". Unless its an OHV the only spring on an engine that size is in the throttle control and the throttle return spring on the throttle shaft. They dont normally wear out and cant be stretched during removal like the throttle springs you're thinking of. In my experience a worn throttle control spring on those engines cause the engine to overspeed or run a bit on the slow side, not spit fire from the muffler and conk out.

Last edited by Skin; 02-03-2011 at 01:40 AM.
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Old 02-03-2011, 07:17 AM   #18
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Default Re: Snowblower runs rough and stalls under load

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...It doesn't have any real adjustments that I can find (just one that controls the throttle). I've done some searching and its seems to be that its running lean (there is also a bit of flame coming out the exhaust from time to time)...
I have a 9HP Tecumseh on mine, yours is doing exactly what mine has doing... I'd get some "pops" with sparks/flames out the exhaust, it would only start w/ the electric starter (needed a good 10s of cranking), and when it was running it would only run full throttle w/ choke full on. Sometimes when it first starts it would run and stall, I'd have to pump the primer bulb to keep it running when I heard it slowing down.

I know this doesn't help you since you have no adjustments, but my machine has two screws under the float bowl--one is a spring loaded drain which off-center (you push it, gas comes out meant for draining off-season) and the other is centered and is some sort of an adjustment, maybe mixture or maybe float. When it starts running like poop I twiddle that center screw left-right a bit until I hear it even out, then it runs great, I can even let the choke open and run it down to an "idle" if I need to shovel, she'll start on one-pull after that adjustment even when cooled off. I'd say every 2-3 hours of running it gets into a "not happy" state, I suppose it's vibration causing the adjustment to go out or something...
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Old 02-03-2011, 07:42 AM   #19
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Default Re: Snowblower runs rough and stalls under load

Torch tip cleaners work well on small passages. You can buy repair CD's on FleaBay for $5-10 that will show you every step to take from A-Z, they are well worth the money. Make sure your intake gaskets are good. Sometimes you have to pop out those little freeze plugs for a good cleaning, new ones come in the carb kit. Don't reuse your bowl gasket, always replace it when rebuilding. If your bowl has a step in the bottom it must be oriented properly. Check youtube, many vid's on rebuilding Tec carbs............Check fuel flow through the tank, a bad vent in the cap will trip you up. The repair CD covers pretty much everything, too much to list here.

Last edited by marnav1; 02-03-2011 at 07:46 AM.
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Old 02-03-2011, 07:57 AM   #20
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Default Re: Snowblower runs rough and stalls under load

Quote:
Originally Posted by KCarGuy View Post
I have a Toro from 1967, runs great. But over years of use, it runs best at an "Over Rich" state, without a load it starts to Load up a bit, but, under a load, it runs strong and never even stumbles.
Another good test was today...18" to 24" snow in Chicago. Did mine and my Neighbors place...4 tanks of Gas, but a Rich Running Toro is a Happy Toro!!!
20" Snowhound? I picked one up a couple months ago for $75. Didn't run right, Put about $30 of parts in it, she's a happy clam. Heavy built little bugger.

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