# Briggs and Stratton 250cc Rough Idle



## bryankloos (Oct 4, 2015)

Guys,

I'm servicing my Airens Deluxe 24 (with B&S 250cc) in preparation for the winter. I did an oil and plug change and cleaned the carb as it was running rough pre tune up. All is good now other than a very rough idle. It runs fine at full throttle but is rough when the throttle is at the lowest position. 

The carb was pretty gummy but I thought I cleaned it pretty well...

Any thoughts as to what to inspect/fix?

The engine is a 2011.

All help is appreciated.

Best,

Bryan


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## 30yearTech (Sep 14, 2006)

If you could provide the Model, Type and Code #'s off the engine that would be helpful in offering suggestions.


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## bryankloos (Oct 4, 2015)

Sure thing.

Its a Briggs and Stratton 1150
15C134 2143 F8
250CC

Its on an Airens Deluxe 24 Snowblower.

It seems the governor is causing the rpm to fluctuate at low rpm...


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## geogrubb (Jul 28, 2006)

A couple things to check, the bowl nut is the main jet for the carb, make sure it is clean, one hole down the center and another across the bottom, the "O" ring behind the carb might be failing or missing, while the engine is running spray some carb/brake parts cleaner behind the carb and along the intake tube, if the engine tempo changes you have an air leak. Have a good one. Geo


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## 30yearTech (Sep 14, 2006)

Did you remove the carburetor to clean it? or did you just drop the float bowl and clean around it?

May still have some build up around the nozzle.


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## bryankloos (Oct 4, 2015)

I removed the entire carb and cleaned it out, though the bowl was pretty dirty and the bolt which holds it on the base of the carb was equally dirty. I shot it with carb cleaner but failed to note it had orifices and holes that may in fact be partially clogged. I will pull the bowl again tonight and ensure the bolt is cleaned well. hopefully that will fix the problem!

Thanks guys!


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## geogrubb (Jul 28, 2006)

bryankloos said:


> I removed the entire carb and cleaned it out, though the bowl was pretty dirty and the bolt which holds it on the base of the carb was equally dirty. I shot it with carb cleaner but failed to note it had orifices and holes that may in fact be partially clogged. I will pull the bowl again tonight and ensure the bolt is cleaned well. hopefully that will fix the problem!
> 
> Thanks guys!


Here is a pic of the nut for reference. Have a good one. Geo


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## bryankloos (Oct 4, 2015)

So I pulled the bolw off again and cleaned out the bolt. It was clean.
Put things back together and still having an idle issue.

Here is a video of the engine running:

Just cut and paste to your browser...

youtu.be/ELBmwUOTMo8

I started out at idle, then slowly increased the throttle up to full, then slowly back down again. You can see the issue. I'm also getting a little popping from the exhaust, though very minor at lower rpms.

Nothing changed when spraying card cleaner behind the carb near the spacer.

Thoughts?


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## bryankloos (Oct 4, 2015)

Think I figured it out... I may have overtorqued the bowl nut and overcompressed the nut gasket. It seems I am not aligning the holes on the sides of the nut with the passages on the tube where the nut screws in...

Could this be the cause of the observed condition? Not getting enough gas at idle cause the path is restricted by the over rotated bowl nut?


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## geogrubb (Jul 28, 2006)

bryankloos said:


> So I pulled the bolw off again and cleaned out the bolt. It was clean.
> Put things back together and still having an idle issue.
> 
> Here is a video of the engine running:
> ...


Here is a link, maybe it will give you some ideas. Have a good one. Geo

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


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## 30yearTech (Sep 14, 2006)

bryankloos said:


> Think I figured it out... I may have overtorqued the bowl nut and overcompressed the nut gasket. It seems I am not aligning the holes on the sides of the nut with the passages on the tube where the nut screws in...
> 
> Could this be the cause of the observed condition? Not getting enough gas at idle cause the path is restricted by the over rotated bowl nut?


No, the holes do not need to line up for fuel to be delivered. Even if that was the case, it would be more of an issue when throttled up then at idle.

I can't tell by the IPL for the carburetor and I am not sure if the carburetor used on your engine has a low speed circuit or not. From the video you posted it acts like the pilot jet is plugged, or the low speed pickup or transition ports are dirty.


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## 30yearTech (Sep 14, 2006)

OK, I went back and had another look at the IPL and I do see a welch plug listed. This would cover the transition ports on the side of the carburetor with the fuel inlet near the mounting bolt. There is a small passage way that feeds these ports from the nozzle, and most likely this is where your issue lies. You may need to remove the welch plug and spray cleaner through the port to open up the passage way, for fuel to flow. You can also check the transition ports when you remove the welch plug. You will need a new welch plug as you destroy them when removing.


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## bryankloos (Oct 4, 2015)

Don't see the welch plug on the parts diagram.

http://www.briggsandstratton.com/us...list?modelnumber=15c134-2143-f8&ipl_id=159895


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## bryankloos (Oct 4, 2015)

Though I certainly see it on my carb...


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## 30yearTech (Sep 14, 2006)

bryankloos said:


> Don't see the welch plug on the parts diagram.
> 
> http://www.briggsandstratton.com/us...list?modelnumber=15c134-2143-f8&ipl_id=159895


I missed it the first time I looked too... It's reference # 127E on the IPL in your link.


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## bryankloos (Oct 4, 2015)

Thanks guys,

I ordered a new whelch plug and a rebuild kit and bowl.
Hopefully this will get things back in action! I'll report back once things are running.

Thanks Again,

Bryan


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