# lawn mower stalling...



## DexterII (Jul 14, 2010)

I would start with the fuel cap. If not venting properly, it can create a vacuum, shutting off the fuel flow. If it appears to be the original cap, clean it. If improvised, get the right one for it. Don't know what it has for a fuel filter, but toro.com has manuals that you can view or download, once you have the model number. After that, I would check to make sure that it has spark at the plug when it quits. Assuming it does, it's probably time for a thorough carburetor removal diassmbly, and cleaning.


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## Oso954 (Jun 23, 2012)

I would start with the air filter and spark plug.
Pull, inspect, clean or replace as necessary.


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## rustyjames (Jul 20, 2008)

Agree with Dexter, try cap first, see how it runs with it loose.


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## RWolff (Jan 27, 2013)

> I don't know how old it is, as it came with a house I bought last fall.


Sort of a "buy this house NOW and we'll throw in a FREE mower to sweeten the deal!" 





> with a B&S engine


Ah yes, the disposable B&S mower engines, built with all the quality a 2 year warrantee for an engine used maybe 20 hours per summer.

My dislike of B&S aside... there's only 2 systems- fuel and spark, if it starts up at all it's getting a spark, that leaves the fuel system as the likely problem, which narrows it down to the carb.

Pulling the rubber gas line off the carb does gas flow or just drip?
If it flows well, then the tank is not clogged with crud on the bottom and the hose is clear, that narrows it down to the carb.

You could still have some intermittant electrical issue like a wire whose insulation is damaged and vibrations make it contact the metal and grounds it stopping the engine, but it's 99% chance it will be the carb.

Over wintering storage the carb can get some gummy residue, the float can stick, or the float could have a hole in it, there could be a minute speck of grit plugging the small jet holes inside.

This might help:

http://outdoorpowerinfo.com/repairs/briggs_walbro_lms_carb.asp

Removing the carb or at least opening the bowl will reveal if the float is freely moving up and down, not full of gas.
If the float looks ok, it can be just some little crud or grit, check that brass bowl bolt you removed to drop the fuel bowl- notice it's more than just a bolt to hold the bowl on, it has a cross-bore and a vertical hole, make sure both are clean as well as the inside where the float is, reassemble and see if there's any improvement.
These carbs are super cheap, the rebuild kits almost cost what the whole carb new costs, more if you figure your time in.
You also will have a bulb primer I presume, the rubber diaphragm and all tends to malfunction, mine is dead and the cost to replace that is ridiculous and I'm not spending money on an old mower I bought years ago used, I just dump a little gas in the intake and it starts right up.

A malfunctioning bulb primer can make starting hard but once running you shouldn't need it to restart.


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## Thurman (Feb 9, 2009)

"Is there a fuel filter that might be clogged?" Yes there is, or should be. Look at the fuel line from the tank to the carb. On all the Toro's I have worked on there was an "in-line" fuel filter somewhere in this fuel line. IF there is not an inline filter then put on in there. Maybe $5 at any auto parts store. Your problem definitely sounds to be a fuel delivery problem. When it sits for a few minutes the fuel will seep by some type of obstruction and give the carb enough fuel to run for a few minutes. Then whatever is slowing the fuel delivery down comes back into play. I would remove the fuel tank, the hose from tank to carb and clean these out to assure there is nothing loose which would be clogging the fuel line. There could also be something in the carb right where the fuel line attaches and this will need to be cleaned out. Actually-IF you feel confident enough: Remove the carb, remove the fuel bowl and clean out all orifices with a carb cleaner.


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## sublime2 (Mar 21, 2012)

I had a very similar issue with my mower. 
My problem was dirt in the bowl. 
There is a bowl under the carb that holds fuel, the bolt that secures that bowl has very small holes in it that allows the fuel to flow. Remove the bolt and clean the holes with a small piece of wire. Reinstall it, prime it and you should be good to go. 
Don't forget to clean the bowl too.


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## RWolff (Jan 27, 2013)

> "Is there a fuel filter that might be clogged?"


Mine doesn't have a filter, there probably should be one on all fuel burning motors, but mine doesn't have one, so you don't always have one on a used mower.


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## Toller (Jan 2, 2013)

*Fixed?*

The mower doesn't have a fuel filter, the gas tank looked clean, and getting at the carburetor would require significant dissassembly.
So I checked the air filter. It was filthy; I am surprised the mower ran at all. Cleaned and reinstalled.
Mowed the lawn today with no stalls.
But it didn't have any more power either; I would think that if it stalled because of a clogged air filter it would also barely run between stalls; and that wasn't the case, between stalls it ran as well as it did today.

So, did I:
1) Fix it by cleaning the air filter
2) have what ever was clogging the gas line just run out
3) get lucky today and it will stall next time


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## sublime2 (Mar 21, 2012)

Toller said:


> The mower doesn't have a fuel filter, the gas tank looked clean, and getting at the carburetor would require significant dissassembly.
> So I checked the air filter. It was filthy; I am surprised the mower ran at all. Cleaned and reinstalled.
> Mowed the lawn today with no stalls.
> But it didn't have any more power either; I would think that if it stalled because of a clogged air filter it would also barely run between stalls; and that wasn't the case, between stalls it ran as well as it did today.
> ...


All of the above.


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## RWolff (Jan 27, 2013)

Toller said:


> So, did I:
> 
> 1) Fix it by cleaning the air filter
> 2) have what ever was clogging the gas line just run out
> 3) get lucky today and it will stall next time


I vote for # 3 knowing how these engines are made 

It takes a minute little piece of grit to clog up the fuel jet in the carb that would cause these issues too, and let's face it, most people have the gas in an old plastic jerry can that's sitting in the garage or shed for years, it never gets rinsed out, it's taken out on the lawn where small grass clippings and grit can get on the nozzle and into the gas.
The gas cap is usually dirty and dusty,with grass clippings etc on it, point is it's extremely easy via any of those avenues to get some junk in the gas tank and into the carb.
A tiny fragment of a blade of grass in the bottom of the tank can intermittantly plug up the little outlet too.
So the first places to look is the carb, fuel filter and line, the air filter and spark plug including it's wire.

I think for my next mower I might look at one with a Honda or Kawasaki engine.


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## Scottg (Nov 5, 2012)

Toller said:


> So I checked the air filter. It was filthy; I am surprised the mower ran at all. Cleaned and reinstalled.
> Mowed the lawn today with no stalls.
> But it didn't have any more power either; I would think that if it stalled because of a clogged air filter it would also barely run between stalls; and that wasn't the case, between stalls it ran as well as it did today.
> 
> ...


Maybe all three. But if cleaning the filter at least helped, maybe it's time to fully replace the filter. That is, are you sure it's truly clean? Or is there stuff still gunked in it somewhere?

In any case, unless I know exactly what's wrong, I always start with the simple and fairly inexpensive stuff which is mostly yearly maintenance anyway. Change the oil, replace air filter, replace spark plug (and check the spark plug gap), replace the fuel filter if there is one.


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## Windows on Wash (Aug 30, 2011)

Do you have Ethanol in your fuel in your state? Ethanol is a real killer on smaller engine carburetors.


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## polarzak (Dec 1, 2008)

RWolff said:


> I vote for # 3 knowing how these engines are made
> 
> 
> I think for my next mower I might look at one with a Honda or Kawasaki engine.



I have used B&S and Tecumseth engines for as long as I can remember (longer than I care to remember) and have never had any issues with them providing one follows your advice about using clean fuel from clean containers. They will last as long and run as well as any other brand. However if you wish to spend double the price for offshore machinery, made from scrap Zeros, be my guest.


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