# Lawnmover won't keep running



## Ron6519 (Mar 28, 2007)

MovedTooMuch said:


> I have an MTD Yard Machines mower with a B&S engine. When I pump the primer bulb, the engine will start and then slowly die and stop.
> 
> I have cleaned the spark plug.
> I have cleaned the air filter.
> ...


Sounds like a carburetor /choke issue. Check the supply hoses for small cracks. But I would assume you would smell raw gas with a leak. When you cleaned the plug, what color was it? If the mixture was rich, the plug would be black with a lot of carbon on it.
Ron


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## Jackofall1 (Dec 5, 2010)

Sounds like a gasket leak between the carb and the cylinder head. Remove clean thoroughly and replace with new gasket. 

Mark


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## MovedTooMuch (Oct 15, 2006)

I don't smell gas or see any kind of leak. 

The plug was black. I have not changed it in years! I did give it a good cleaning and the mower operated the same. I also have a new spark plug that I will install soon.


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## Bondo (Dec 8, 2007)

> What I noticed last season was that the gas would not run all of the way out when the mower would shut off. As the season progressed, I needed to keep topping off the tank after 1/2 the yard (and I have a really small yard). I used to be able to mow my lawn at least twice without refilling the gas tank.


Ayuh,... It's obviously running out of gas, so figure out *Why* it can't get it's gas...
Is the tank full of crap,..??
The fuel lines,..??
Maybe even the carb itself,..??


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## Ron6519 (Mar 28, 2007)

MovedTooMuch said:


> I don't smell gas or see any kind of leak.
> 
> The plug was black. I have not changed it in years! I did give it a good cleaning and the mower operated the same. I also have a new spark plug that I will install soon.


The black on the plug is a symptom of an overly rich mixture not the length of time it's been used. 
You need to look at the choke and the carb.
Ron


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## waterman1971 (Apr 19, 2009)

Look for tears or cracks in the little pump bulb primer thing. This issue shut my leaf blower down a couple of weeks ago. Luckily,I was able to rob one from an old weed eater.


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## MovedTooMuch (Oct 15, 2006)

Thanks for the answers. 

The bulb primer does not show any signs of a leak or tears.
I have adjusted the choke. That does not seem to alter the problem.

I am going to do this list before changing gaskets. 

Replace the spark plug
change the oil
Refill the gas with fresh gas (it was pretty old since the yard is so small and had stabil in it.)
Get some carb cleaner
I did get the details on the engine model. 
Model: 10A902
Type: 22189B1
Code: 00060955
Parts Page


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## piste (Oct 7, 2009)

I've been wrestling with a similar problem in my B&S engine (diff model) in my Toro for the past few years. Had the dealer chase it down to the aforementioned gasket but that fix only lasted a month or two. At the moment my only solution is to pull the carb apart every 4 weeks or so during the mowing season and clean it well which resolves things....for a short while. Honestly I think the B&S engines (and most small engines) these days are hypersentive to the ethanol in gas. Mine is an auto choke which is also a crappy way to go and I'd swap it out for manual choke if I could figure out how.


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## waterman1971 (Apr 19, 2009)

piste said:


> I've been wrestling with a similar problem in my B&S engine (diff model) in my Toro for the past few years. Had the dealer chase it down to the aforementioned gasket but that fix only lasted a month or two. At the moment my only solution is to pull the carb apart every 4 weeks or so during the mowing season and clean it well which resolves things....for a short while. Honestly I think the B&S engines (and most small engines) these days are hypersentive to the ethanol in gas. Mine is an auto choke which is also a crappy way to go and I'd swap it out for manual choke if I could figure out how.


Ding Ding... you are the thread winner!!:thumbup:


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## piste (Oct 7, 2009)

waterman1971 said:


> Ding Ding... you are the thread winner!!:thumbup:


Excellent!! What's my prize? :laughing:

If the ethanol is the culprit...every homeowner needs to learn how to clean a small engine carb...with 5 small engines to support...I'm glad I did. 

lawmower, power edger, pressure washer, string trimmer, snow blower


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## waterman1971 (Apr 19, 2009)

piste said:


> Excellent!! What's my prize? :laughing:
> 
> If the ethanol is the culprit...every homeowner needs to learn how to clean a small engine carb...with 5 small engines to support...I'm glad I did.
> 
> lawmower, power edger, pressure washer, string trimmer, snow blower


Or, if nothing else, run it dry if not being used for extended periods of time.


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## piste (Oct 7, 2009)

waterman1971 said:


> Or, if nothing else, run it dry if not being used for extended periods of time.


Well...my Toro may just be a lemon...but in the summer I use it at least once a week...and can't seem to get it to run well for more than a month or so before it starts acting up. Then a good carb clean gets it going again. In addition to ethanol, the automatic choke is a real problem...and if I ever find a conversion spec I'll be making that change. And the maintenance shops are making a killing cleaning these carbs at $40 a whack or so and then telling you that you used "bad gas" when you are actually using premium grade that is only a month or two old and with StaBil added to it. Not like decades ago with dad's old mower that just ran for years with nary any maintenance of any kind whatsoever.


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## CHOPS! (May 29, 2011)

So.....
You've installed the new spark plug.
You've installed a new air filter.
You've cleaned the jet on the nut which holds on the carb bowl.
You've tightened the two bolts VERY GENTLY which join the carb with the manifold.
You've made sure the gas tank is clean and has fresh gas.
You've changed the oil and put in the proper SAE 30W oil (20 oz.)....

AND THE MOWER STILL STARTS AND THEN DIES!!???:furious:

DO NOT MELT DOWN JUST YET!:no:

I had this problem and I think I found the formula for the long term fix. If you have the skills and tools to take off the red cover AND the black metal cover which houses the start cord mechanism - here's what you do:

First, take a small wire brush (a 1/2" copper fitting brush works very well)and clean off the magneto surfaces on both the coil and the flywheel. If you don't know where this is, just follow the spark plug wire from the spark plug up to the coil and there it is. There is one surface on the flywheel and three surfaces on the coil.

Secondly, there is a very short black hose leading from the carb to the engine which you cannot get to without removing the black metal cover. This hose comes from the factory without clamps, and from what I could figure out, with age this hose loses vacuum when the engine gets warm and the hose expands slightly. That's why the mower will run fine for a few minutes and then all of a sudden after the hose warms up a little, expands and loses vacuum, the mower does the start and die routine which we all know can drive you nuts.
Get two spring-type hose clamps which are identical to the ones attached from the gas tank to the carb. These are available at Ace hardware for around 40 cents apiece and they are 1/2" O.D. size. PUT THESE CLAMPS ON THE SHORT BLACK HOSE. This is the "secret" ingredient to the long term fix.

Put the covers back on. Don't overtighten the bolts. And get back to work!:thumbup:


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## piste (Oct 7, 2009)

*A Followup..*

Followup to my situation....pulled the carb apart like I'd done once or twice last year....but this time I soaked the parts in B-12 Chemtool which was recommended to me. Soaked them like 48 hours or so. Put everything back together and she's been running like a champ for the past two months or so. Also changed another thing. Started using a 2 gal plastic gas can instead of the old surplus jerry cans I have. So those could be the culprit but I'm guessing it was more like the B-12 Chemtool cleaning that did the trick.


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## 95025 (Nov 14, 2010)

waterman1971 said:


> Ding Ding... you are the thread winner!!:thumbup:


Actually, when we did our lawn-mowing service, we ran 10% ethanol in all of our mowers for years (state mandate that all gas had 10% ethanol), and it never affected them in any negative way.


It sounds to me like the OP has a dirty carb. The tiny orifices in those small engine carbs are extremely sensitive to any little bits of dirt, rust, or grass.


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## 95025 (Nov 14, 2010)

piste said:


> Followup to my situation....pulled the carb apart like I'd done once or twice last year....but this time I soaked the parts in B-12 Chemtool which was recommended to me. Soaked them like 48 hours or so. Put everything back together and she's been running like a champ for the past two months or so. Also changed another thing. Started using a 2 gal plastic gas can instead of the old surplus jerry cans I have. So those could be the culprit but I'm guessing it was more like the B-12 Chemtool cleaning that did the trick.


Guess I should have read this post before commenting on the last one.

Is there a gas-line filter on your mower? If not, it might be a good idea to install one. That'll keep little tiny "bits & pieces" out of your carb, where the stuff will plug the orifices.


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