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Author Topic: Why wont my Stihl keep running?  (Read 5667 times)

Offline A.O.

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Why wont my Stihl keep running?
« on: January 30, 2019, 08:07:01 AM »
So I have one of my older saws a MS250 (I think) anyway, I haven't ran it for a month or so, filled it up with fresh gas yesterday, It seems to start fine, but wont keep running. I pulled the filter out and it looks like new, so what else can it be?

Offline Ox

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Re: Why wont my Stihl keep running?
« Reply #1 on: January 30, 2019, 09:21:57 AM »
Fuel lines is a good place to start.  If you've ever had the ethanol fuel in it they are deteriorated.
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Offline bandmiller2

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Re: Why wont my Stihl keep running?
« Reply #2 on: January 30, 2019, 10:03:26 AM »
The poor fuel we have now is tough on carb diaphragms you could try opening the main jet slightly or give it a small sniff of starting fluid. Sometimes if you can start with fluid they will stay running. As always try a new plug as once the fuel wets the electrodes their loathed to start. Frank C.

Offline furu

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Re: Why wont my Stihl keep running?
« Reply #3 on: January 30, 2019, 10:51:13 AM »
Fuel lines on the older saws 0XX (026 044 etc) are not ethanol friendly.  If they have not been replaced they need to be.  If it is a MSXX0 model saw such as your MS250 then according to Stihl the lines are ethanol safe but the carb is not.  Never let ethanol gas for your saw sit for longer than a week, PERIOD.  If you don't use it up in that time frame you mixed too much. 
I use ethanol free fuel in all my 2 cycle engines. It has a good shelf life but mine rarely last more than a week often much less and I mix 2 gals at a time.
Some area it is hard to find other areas just more expressive.   
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Fuel lines are a place to start. Impluse line, fuel filter (pickup body as Stihl calls it)
What condition is the plug in. Color etc.

You said it ran fine a month or so ago.  Sometimes a month or so ago is 1, 2, or 6 months sometimes 12 months as we lose track of time

Was fuel left in it a month or so ago?

When you stated your issue I immediately thought the following as I have had all of the below and not always the same reason at one time or the other:
1, Does it start and then die without really running?
2, Does it start and idle for few seconds and then die?
3. Does it start idle fine but when run WOT then die as it idles down?
4, When it dies is it a clean die or does it struggle as it dies?
5. Does it start idle but die when you throttle up?

Edit add on:  which 2 cycle oil do you use in your mix?
Integrity is not just doing the right thing.
Integrity is not just doing the right thing when no one is looking.
Integrity is doing the right thing when no one else will ever even know.

Offline A.O.

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Re: Why wont my Stihl keep running?
« Reply #4 on: January 30, 2019, 11:52:30 AM »
Ok, Update and answers for questions..

My memory is not as good as it once was the saw is a MS260, not 250 not that I think it matters.

I'm using Stihl HP ULTRA 2 cycle mix. I've always used the Stihl mix, other than the rare occasion I need something NOW and no Stihl stuff for sale close by. I mix it with premium gas (Ethyl ;-0 ). That said, it ALWAYS has ethanol anymore, pretty much has for 20+ years right? I have a one gallon can I use, I fill it and use it till its gone, be it one day or 2-3 months.. I've done it this way for 30-40 years without too much of an adverse effect. Never done it for a living, just for myself, be it for clearing and/or firewood and now "log farming". So I don't always use up the gas quickly.

I'm going with answer #5 on your list furu "5. Does it start idle but die when you throttle up?" If I would throttle up slowly it would almost make it to speed, if I just pegged the gas it would just die.
However... I just fired it up and it seems to run fine today..the other day I dicked with it for an hour and could never get it to run WOT!

And yes it truely was about 1 month ago.. And I am unsure if it had fuel in it when I parked it or not. Looked pretty dry when I filled it the other day.


Offline furu

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Re: Why wont my Stihl keep running?
« Reply #5 on: January 30, 2019, 12:07:44 PM »
If the pickup body (filter) is getting old then they start to deteriorate and small particles break loose and make it to the carb.  That can cause idle problems (ask me how I know that one, HA HA) as well as WOT issues.  The 260 has both hi and low mixture as well as low idle settings.  They can be adjusted. 
Sounds like your issue is gone for now at least. 
Congratulations  That is the easy kind of fix.  Hope that it does not return.
Integrity is not just doing the right thing.
Integrity is not just doing the right thing when no one is looking.
Integrity is doing the right thing when no one else will ever even know.