chainsaw keeps stalling

branchmanagerSeptember 21, 2011

I have a ms220 that starts fine with the choke but cuts out when full throttle is applied. Is it the carburator? If so is there a repair manual on line so that i can strip the carb

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Sounds like routine fuel starvation. Check your carb diaphram prefilter and inline filter 1st . Then ensure you have fresh fuel and fuel treatment (full tank). Let the mix sit for approx 20 minutes and then try a restart , let the saw idle until warmed up then gradually run up the rpm . You may have to turn the low speed jet in or out a little to get the hesitation resolved. Once this has been achieved set up the high speed jet . Turn the screw in until max rpm is met with throttle at full then turn it back out until it gallops then turn back in approx 1/4 turn . This will give you a safe air to fuel ratio .

Note: Make sure your air filter is clean along with a fairly new spark plug for best tuning results .

    Bookmark   September 21, 2011 at 8:21PM
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No such saw model, you need to go through the carb and inspect the fuel line/filter.

Never/ever try to adjust out a running problem...


    Bookmark   September 21, 2011 at 8:29PM
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Fish: You really need to learn saw mechanics . The OP probably had a typo Model may be a 230 or a 200 , no big deal . As for tuning out the problem if you were not such a moron , you would clearly see that I advised to check Carb and Fuel Filter 1st . Instead of jumping in and looking like the chump that you are try applying some basic carb cleaning techniques . Even my Grandechild realizes that the orifice needle configuration can be self cleaning by simple adjustment in conjuction with fuel treatment addition , when warranted. I really love when you drop by for your words of wisdom NEVER EVER tear into a carb fuel circuit without due cause . I have seen more rookies ruin a perfectly good carb by scratching a seat or crack or tear a o-ring or diaphram when simple tuning will clear small restrictions . Yes if all else fail carb internal orifice and circuit inspection and cleaning with a tag wire (carefully) and compressed air may be necessary .

    Bookmark   September 22, 2011 at 6:01AM
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The reason you don't try to adjust out a running problem
is that it masks the problem, and adjustments might relieve the problem initially, piston damage usually results.
I only noted the Model number mis-state, is that certain models have had problems in different areas.

For example, the MS210, MS230, Ms250 saws are well known
for fuel lines getting cracks above the fuel tank, before
entering the carb, and listening to an absolute moron telling you to adjust out the problem could result in piston/cylinder damage.

If it is a MS170, there are no carb adjustments.

So if you can confirm the Stihl model number, I could give you better advice.


    Bookmark   September 22, 2011 at 8:30PM
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What is a "carb diaphram prefilter and inline filter"??

Do you mean the fuel filter at the end of the fuel line and
the inlet screen INSIDE of the carburetor?

The MS 170,MS180, MS210, ms230, ms250 saws are known to have fuel line problems with todays gas, the MS170/ms180 have no adjustment screws, most of the others only have a lo mixture screw, and if you find a bad fuel line, the carburetor is full of crud too most of the time, and needs to be cleaned.


    Bookmark   September 23, 2011 at 9:52AM
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I think some popcorn may be required for this thread.

    Bookmark   September 23, 2011 at 6:04PM
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Fish : Yes the Carb Diaphram Inlet Needle Valve Prefilter Screen last time I looked was an internal carb component and an Inline (Fuel) filter within the tank or positioned within the fuel line just prior to the carb . As for fuel delivery line or vacuum (crankcase) lines contributing to a over lean mixture and potential piston or ring seizure during carb tuning it is very remote. Any significant air entrailment during operation would be evident from residue or leakage (leakdown) during shutdown . I really doubt any serious issue would even allow tuning if the fuel lines were of this nature. I agree that fuel line blockage or breakdown is an important factor to determine during prestarting or preseasonal servicing , that is why I advised of the proper tuning techniques , fresh (treated fuel) close to A full tank along with clean air filter and sparkplug.

Note: Having Raced and Tuned Numerous Snowmobiles and Moto-X Bikes during over 50 yrs , I really think I have a good grasp of when Teardown is warranted and when preventative or proactive fuel treatment and fine turning may well cure a small hesitation within a running saw . Anyhow since the OP has not chimed back in since Wed he has most likely solved the mystery by now and I just ran out of butter for my next batch of Popcorn ...Chow :)

    Bookmark   September 24, 2011 at 12:47PM
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