Won't start Stihl MS-250

njtrout(z6 NJ)June 27, 2006

I inherited a almost new Stihl MS-250 chainsaw. It was new in Winter/Spring 2004. I am sure it was only used a couple of times. It sat in a garage with fuel in it since that time. I tried to start it with the existing fuel. It started once for a few minutes. Great I thought, mixed up fresh fuel and added it to the tank. Since then I cannot get it to start. Before I bring it to a dealer for service is there anything else I can try on my own? New spark plug? Air filter is clean. Topped off the chain oil. The chain does move properly and feels tensioned well. I'm new to chainsaws as well and want to keep things safe. I do apply the chain break when starting.

Thanks in advance.

NJTrout

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canguy(British Columbia)

Remove the air filter and give it a small spritz of gas in the carb throat. DONT use starting fluid. If it fires and quits it is not getting fuel and needs a good servicing. Two year old fuel is hard on fuel lines and carb diaphragms.

    Bookmark   June 27, 2006 at 5:53PM
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davefr

Several factors must come together to start a small gas engine. You need fuel, air, compression, and ignition.

Let's start with the basics:
1. Is the tank full of fresh fuel? Is the air cleaner element clean? Is the spark plug lead attached to the plug? Are you following the correct starting procedure?

2. If the items in #1 check out then let's take it to the next step. Pull the spark plug, connect the lead, and ground the base. Give the starter a strong yank. Is the plug arching? (you can also use a spark tester or use the screwdriver trick). If there's no sign of a spark you could have a bad ignition module or high tension wire.

3. Now if you're getting spark, you also need fuel and air and the spark must be ocurring at the correct timing. An easy test is to pour a teaspoon of gas in the cylinder and try and start the saw. If it fires briefly then dies your problem could be carburation/fuel delivery.

4. Check the condition of your fuel line. They often deteriorate into mush or develop cracks so they pull air vs. fuel. Now check the pulse line. It can't have air leaks or you won't be getting pulse action to the carb. (This serves as a fuel pump).

5. If fuel line and pulse line look OK you need to focus you attention on the condition of the carburator. This is very susceptable to problems if the saw wasn't used for several years yet still had old fuel in it. The best bet is to rebuild the carb with a new kit and blast the body and all the tiny passageways with carb cleaner. Blast the cleaner in both directions. An ultrasonic cleaner is also an option.

6. The above should help you with simple starting problems. I did not cover other issues such as gross seal leaks, low compression, or bad timing. If the saw ran fine last time you used it then these are unlikely. For further diagnosis you're better off taking the saw to a shop.

    Bookmark   June 27, 2006 at 6:54PM
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njtrout(z6 NJ)

1. Is the tank full of fresh fuel? Ans. It started once with old fuel. I added fresh mix on top of that and since have not been able to start it.

Is the air cleaner element clean? Ans. Yes
Is the spark plug lead attached to the plug? Ans. Yes
Are you following the correct starting procedure? Ans. Yes

The rest of the test will have to wait for the weekend.

2. If the items in #1 check out then let's take it to the next step. Pull the spark plug, connect the lead, and ground the base. Give the starter a strong yank. Is the plug arching? (you can also use a spark tester or use the screwdriver trick). If there's no sign of a spark you could have a bad ignition module or high tension wire.

3. Now if you're getting spark, you also need fuel and air and the spark must be ocurring at the correct timing. An easy test is to pour a teaspoon of gas in the cylinder and try and start the saw. If it fires briefly then dies your problem could be carburation/fuel delivery.

4. Check the condition of your fuel line. They often deteriorate into mush or develop cracks so they pull air vs. fuel. Now check the pulse line. It can't have air leaks or you won't be getting pulse action to the carb. (This serves as a fuel pump).

5. If fuel line and pulse line look OK you need to focus you attention on the condition of the carburator. This is very susceptable to problems if the saw wasn't used for several years yet still had old fuel in it. The best bet is to rebuild the carb with a new kit and blast the body and all the tiny passageways with carb cleaner. Blast the cleaner in both directions. An ultrasonic cleaner is also an option.

6. The above should help you with simple starting problems. I did not cover other issues such as gross seal leaks, low compression, or bad timing. If the saw ran fine last time you used it then these are unlikely. For further diagnosis you're better off taking the saw to a shop.

    Bookmark   June 27, 2006 at 10:21PM
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fisher40037

You will likely need to replace the fuel line(full of cracks
), and rebuild the carb, which is real common on this model.

Fish

    Bookmark   June 29, 2006 at 9:25PM
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den69rs96(z6CT)

Since the saw was used only a few times and is somewhat new, I hope you don't need to replace the fuel lines. Still it would be wise to check them for cracks. I would replace the fuel filter as well. I had a similar problem with my robyi trimmer. I started with old gas and seemed to run fine. Then after a few minutes it wouldn't run. I was able to get it running again, but it would only run with the choke on and then would die if you tried to give it gas. I replaced the gas with fresh gas, changed the spark plug and took the side covers off the carb and cleaned it with carb cleaner. I put it back together and started first pull after that. You would be amazed what bad gas will do.

    Bookmark   July 1, 2006 at 3:03PM
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njtrout(z6 NJ)

Well, good news. I decided to give it one more try over the weekend. Tried with throttle in 'cold' start position but no go. Switched to warm start and wham-o. It started. Threw alot of smoke for the first minute, but then cleared. I ran it for about 15 minutes varying the throttle speed. Stopped it...pulled to a start first try. The only thing i noticed was it was throwing globs of grease from the bottom of the saw. I suspect this normal. There was oil from the chain on the ground so I no it is oiling properly.

Thanks for the advice. I will be replacing the fuel filter no matter what.

Now another easier question. Does anyone have plans for a stand to "buck" logs? I've seen pictures, but would like specs or plans to build one.

Thanks,
Andy

    Bookmark   July 4, 2006 at 11:27PM
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canguy(British Columbia)

Sounds like you over choked and flooded it. When it is cold and on choke, pull it till it pops once then bring the lever to warm start. Glad you got it going, that is a good light duty homeowner saw

    Bookmark   July 5, 2006 at 12:31AM
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njtrout(z6 NJ)

Now, wouldn't you know it, I've used it over the summer, started on first pull. Tried today, and it won't start. It is stored in a cold garage. Do chainsaws need to be sitting in the hot sun and backing before they will start?

* Replace the spark plug today, just in case. The old one was in great condition, but you never know. No Start

* Tomorrow, I'm planning on bringing it into the warm house and letting it warm up before starting. Temps have been 25 at night 50 during the day. Store in the attached garage.

* Turned the air baffle to th cold position per the Stihl instruction manual. No Start

* Per Stihl instruction manual, I removed plug, gave it a few pulls to clear the cylinder, replaced plug. No Start.

If I have no luck with a "warmed up" up saw tomorrow, I'll replace the fuel filter - looks like a DIY type of project.

Andy

    Bookmark   November 25, 2006 at 9:29PM
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fisher40037

You need to use a batch of fresh fuel mix. After a month, today's fuel gets bad, and makes for hard starting.
Also fuel is formulated different in summer, than winter. Winter grade fuel is formulated for colder temps
and makes for easier starting.

Fish

    Bookmark   November 26, 2006 at 7:01AM
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njtrout(z6 NJ)

Well, whata ya know. It started. I think I have been over choking the saw all the time. I gave it 2 pulls on cold and then switch to the warm setting and it started right up. Ran like a charm all day. Guess, I'll avoid using the cold setting from now on.

NJTrout

    Bookmark   November 26, 2006 at 10:36PM
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tahclep(PA)

Use a good oil for saws such as Stihl, Echo or Hushy etc. I know the Stihl and Echo have fuel stabilizer already in it so you should be good for several months with no problems.

    Bookmark   November 29, 2006 at 9:04PM
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njtrout(z6 NJ)

I have been using the Stihl brand oil mix and bar/chain oil.

What is the shelf life of the oil mix?

NJTrout

    Bookmark   December 7, 2006 at 5:13PM
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canguy(British Columbia)

The stabiliser manufacturers claim up to 2 years but I don't push it. Anything older than 6 months goes in the truck (usually less than a gallon)

    Bookmark   December 8, 2006 at 9:56AM
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gandalf65

hi all. just wanted to say hello to u all as this is the first time i have been on ur site. i was looking for some information as to why my chainsaw wouldnt start but it looks like it is nackered...lol.
some1 who repairs them said the piston is away, it is a Stihl 024. need to go buy a new 1 then. can any1 tell me the best place in the uk to go look for 1.. im in Scotland. tyvm for listening to me... t/c all

    Bookmark   September 19, 2007 at 6:40PM
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gandalf65

hi all. just wanted to say hello to u all as this is the first time i have been on ur site. i was looking for some information as to why my chainsaw wouldnt start but it looks like it is nackered...lol.
some1 who repairs them said the piston is away, it is a Stihl 024. need to go buy a new 1 then. can any1 tell me the best place in the uk to go look for 1.. im in Scotland. tyvm for listening to me... t/c all

    Bookmark   September 19, 2007 at 7:07PM
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oklahomagreg(Oklahoma)

You are on the right track. I just bought a new one a few months ago. The dealer told me to listen for any sign of it starting then switch to "fast idle". I could rarely hear any difference on the 1st few pulls. Now, I will pull it once or twice on choke then switch to the fast idle setting where it usually starts on the next pull or two. No problems since then but it drove me nuts trying to figure out what was wrong. Good luck with it now.

    Bookmark   October 15, 2007 at 5:59PM
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destroyingangel(5)

Hey gang, thanks for all the useful info. I've got an MS250 that I bought last winter (2008)for like $300+/-. It ran great last winter and into the spring, but it has sat since then with some gas in the tank. I went to start it this past weekend and it won't start. I'm familiar with proper starting procedure and swapped plugs with another saw to verify that I have a good plug. Other saw (Poulan) started fine with the Stihl's plug, but not vice versa.... just called the place I bought the saw from and he says in all likelihood I'll need a new carburetor! ($85-$125!!!!) Says he replaces LOTS of carburetors (20-30 a month!)because people don't know how crappy today's gas is.
My question is - if he's right about the bad gas, could this really ruin my carb or should I be able to clean it and put fresh gas in?

PLEASE HELP - I can't afford a new carb!

Thanks,

Joe

    Bookmark   August 13, 2009 at 12:50PM
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masiman(z7 VA)

First dump the old gas and put in fresh gas. Try starting it.

If that does not work, consider getting a carb kit. It basically has the replaceable parts of a carb in it. Remove, take apart, thoroughly clean, replace gaskets and filters, reassemble and try to start again.

Hopefully new gas will get it to start. If not hopefully it will just be a carb rebuild that will do it.

Use fuel stabilizer from now on. It is fairly cheap insurance for your small engines.

    Bookmark   August 13, 2009 at 2:39PM
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zen_man

Joe,

"Says he replaces LOTS of carburetors (20-30 a month!)because people don't know how crappy today's gas is."

Today's gas isn't that bad, but six-month old gas left in the saw isn't good.

"...if he's right about the bad gas, could this really ruin my carb or should I be able to clean it and put fresh gas in?"

I don't know how gas could "ruin" your carburetor. Perhaps he was referring to gas with added ethanol. Ethanol might attack some old style gaskets. But you shouldn't have to replace a whole carburetor to replace a gasket.

It might be sufficient to pour out the old gas and replace it with a fresh gas/oil mixture. I think it is a good idea to use the highest octane premium gas available in your area. At least, that is what my Stihl dealer in Maine told me, and I see no harm in using the premium gas, but definitely try not to use alcohol gas in your saw. Some people think that is a bad idea, although there are areas where alcohol gas is all that is available.

I'm sure you know that you shouldn't store your saw with gas/oil mix in it. Your Stihl dealer sounds a little "flakey". Is there another Stihl dealer handy in your area?

ZM

    Bookmark   August 13, 2009 at 2:45PM
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creative1448_hotmail_com

My MS250 is brand new. The dealer told me "3 pulls on full choke and you just flodded the carb" "5 pulls and you will not start it unless you dry the plug" He was right. I have a tendency to flood this thing. I'm a slow learner but now I do not choke at all. 70 degree weather.....no choke at all and it starts. If I get anxious I flood the damn thing but I'm learning

    Bookmark   February 27, 2011 at 10:34AM
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ewalk

Woody : Don't fret it all the newer Stihl saws are EPA lean running units (easy to flood) . Ensure you use premium oil and fresh fuel . If you have ethanol based fuel you may experience further hard starting a carb fouling issues if you store fuel for more than a mth or longer . Since your in florida moist air will compound this problem . You have a good homeowner saw for your needs . I usually advise to only mix small batchs of fuel for occasional users and use stabil and or fuel cleaner additives annually to help reduce carb circuit fouling issues . All the Best with your new unit .

    Bookmark   February 27, 2011 at 10:52AM
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