Chainsaw Won't Start? Carburetor Replacement On Stihl MS250C

Chainsaw Won't Start? Carburetor Replacement On Stihl MS250C
In this video I show you some symptoms of a defective carburetor on a chainsaw and how to replace it!
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Easy to follow and thorough step by step tutorials do it yourself (DIY) videos to help you with your broken lawn and garden equipment including snowblowers.
I do my best to teach you how to easily diagnose problems the fastest, quickest and most efficient way with real repairs beyond just replacing a spark plug. These tips are for both the homeowner and shop owner.
Whether it be a handheld, two stroke, two cycle engine like a chainsaw, weed eater, weed wacker, string trimmer, grass trimmer, line trimmer, hedge trimmer, strimmer, brush cutter, leaf blower, or four stroke, four cycle units like a lawnmower, wood splitter, lawn tractor, zero turn mower, snowblower, pressure washer, generator or a ride on mower that needs parts installed or replaced, I’m your go-to guy.
My favorite brands of spark plugs are NGK and Champion and are the ones I recommend.
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Due to factors beyond the control of DONYBOY73 “The Small Engine Doctor”, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. DONYBOY73 “The Small Engine Doctor” assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. DONYBOY73 “The Small Engine Doctor” recommends safe practices when working with power tools, hand tools, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of DONYBOY73 “The Small Engine Doctor”, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not DONYBOY73 “The Small Engine Doctor".
#donyboy73 #smallengine #rideonmower

[@2HAMMERS1]

Dony Boy, you should have a TV show every Sunday. All in Favor...hip-hip

[@snetsky100]

John Smith Hooray!

[@Quadflash]

Donyboy, you just saved me a lot of cash. After watching this video, I replaced the carb on my temperamental 261. Now, it runs like a new saw. I saved $70-80 bucks on labor. Thanks!!

[@fegolem]

I have a old Stihl HT75 pole saw that did the same thing. Hard to start and useless. Bogging. Cleaned and put a kit in it. Very little improvement. Bought an after market carb. (full carb and kit was same price.) New carb has all the adjustments. Old carb had hardly any adustments. Works perfectly, now.

[@tedhumphries1759]

Would have been nice if you had explained how to remove the choke and throttle linkage to remove the carb initially. Had to wait till the re-install to figure out how to remove them initially. The rest of the presentation was fairly good.

[@zx8401ztv]

Smashing, that new carb made a hell of a difference, snappy throttle and performs like new :-D That shows that no amount of carb cleaning will recover some carbs, deep passageways can be impossible to get to.

[@Frankzeien]

Awesome thanks my MS250 just started doing the same thing but not only does mine bog down it dies, and so I went and got a new card that I’ll be putting on tomorrow. Now that I know how to do it. Thanks so much for putting this out there for us to use.

[@jpal5221]

Thanks donyboy73 for the video - great example of an excellent mechanic AND teacher!

[@barrybebenek8691]

OEM costs more, but really it’s the way to go. 👍🏼 Sometimes the playing-around after with less quality stuff, just isn’t worth it. Also Don....that is the COOLEST SHIRT EVER!!! 😁👍🏼👍🏼🏎🚗🚕 (link to that shirt! Lol)

[@bigpicturethinking5620]

Pitting and erosion of critical tolerance surfaces and passages. No amount of gasket changes, welsh plug changes seals or adjustment will help.

[@aleblanc3547]

Sometimes the carburetor just can't be brought back to life...one of the worse things the government did was to force ethanol fuel onto the market. I wonder how much it has cost verses how much it has saved us. I gladly pay an extra $.50 a gallon for non-ethanol fuel especially for my small engines. Thanks Don!!

[@ScottLRoyal]

Another great video. Sitting here with my new carb for a MS 270 and now I know to NOT adjust the screws. Thanks for the help.

[@codysperling833]

I have started a small business now because of donyboy73 and simply working on chainsaws for myself

[@jamesmullins3219]

great video. good tips, good photography & edits

[@earnesthatcher5325]

Very informative, and made simple to understand.

[@Neighborhoodgo2guy]

As always, great video Don

[@holdemNE1]

Great and helpful video, thanks for posting

[@alexanderraykhert1019]

*YES!* Always throw all my things to do aside when I see your videos! Another great one Don!

[@donyboy73]

thanks

[@alexanderraykhert1019]

donyboy73 Keep up the great work!

[@tonym6920]

Great job Dony!

[@dmatthews251]

Dony, Thanks for all the videos! What is the part number for the t-handle wrench you were using?? I recently had a customer bring in a similar saw and I could barely get a nut-driver on the nuts due to their thicker sidewall. It was a struggle but I was finally able to wiggle a socket into the space to get them back in. I knew there had to be a special tool somewhere!! I run a small engine repair business too. When a customer brings in something new or I develop a brain freeze moment, I often check to see if you have a video on the issue before I spend time searching through articles, blogs and forums for an answer. I must say, you’ve saved my bacon once or twice!

[@M0ntaroo]

Awesome video as always !

[@mohsenkiae5462]

Great video thanks !! 😎

[@63256325N]

Thanks for the video.

[@faheemhassanhassan4603]

Good job

[@trumpzilla4193]

Much appreciated!

[@scottwillis5434]

A bit more about unhooking the carb linkages would be great!

[@CTmoog]

Great video!

[@paulmorrey733]

Thanks Don - Great video

[@christianbrignoni2188]

Dante Brignoni 30.05.2020 Switzerland Bravo ottima spiegazione sei forte Ciao

[@marcusjenkins]

Excellent. I just changed the carb on my 14 year old MS210 which was also bogging down (and then not running at all) once warm. I used a cheap Chinese carb and, for sure you're right, I need to adjust the hot Idle downwards.

[@samkaplitz9036]

How do you get the "red" limiter caps off the l&h screws?

[@djaydeved]

i have a kinda old ms171 and i rebuilted the carburator and i got it way outa tune so yay i got to re tune it

[@aj9270]

great video as always Don .... sometimes you're money ahead just changing the carburetor right from the get go in this situation this damn ethanol gas is no good I only use VP ethanol free 4 cycle and pre-mix in all my power equipment this way it's worry free

[@videodistro]

My brother gave up ever buying a Stihl again because they started using crappy carbs, and they knew it and would not warranty them. This is a known issue with Stihls.

[@clauslundberg9224]

Nice to see a chainsaw video - thanks for sharing

[@larrymunday7519]

The thing I have found wrong with those carbs when a rebuild kit has no effect is the o-ring on the accelerator pump. Yes, it has an accelerator pump. It is buried behind the throttle shaft and when the o-ring is bad it sucks too much air and will never run right. You can pull the little brass piston out and JB Weld it back in place. No more leaks or problems.

[@geojor]

good stuff, Dony ...

[@999thenewman]

Replacing with new should be a common practice for chainsaws. :D Reduces the return visits.

[@jerrywhatsworth3589]

Very good video!!

[@johnkosheluk1041]

Just so you know I am a stihl tech those saws like the ms170 180 are known for carb problems

[@jorgeortega1709]

@J Stanlee I would get rid of the self adjusting carb on those saws, they are pure crap. Swap it out for a Walbro WT215, they are functionally similar and work much better on the MS170,MS180

[@dagrote1]

170's are awesome, and around here you can pick one up for less than $200.

[@matthewturowski8281]

Good video. My MS 270 hadn't been run in a couple of years, but had been run dry before storage. Had these same exact symptoms when I tried to run it about two weeks ago and figured it was gunked somewhere. Saw the fuel line was cracked, replaced that, no real difference. Disassembled carb and cleaned it, no difference. Figured a rebuild kit would solve the problem and put a walbro kit in, no difference and adjusting the low side needle made no difference at all. Figured it was sucking air somewhere, but I didn't have a leak detector, so I went ahead and replaced the crank seals and put the old carb back on, no improvement. Even checked the spark arrestor screen, it was clean. I had one more ace up my sleeve-- My last resort was to install the new walbro carb I had bought. Problem solved, ran the saw for 3 hours today with no problems. It is a mystery to me why the rebuild kit didn't solve the problem. Luckily the rebuild kit and crank seals weren't that expensive as they didn't solve the problem. I really didn't think it would need a new carb, lesson learned.

[@Zombeegun]

What I really want to know is how do you clean those saws up so nice?! In your videos it looks like you're working on new equipment. The stuff I work on looks like it's been buried in a bog for 50 years. Do you power wash this stuff? Great videos btw, easy to see and follow. subscribed!

[@darrylclaxton7473]

Good video. What makes those carburetors go bad. I took mine all apart clean and blew it out the holes... And still dont work right..

[@josemenjivar4336]

Awesome video!!!!!!!!! Thanks from Cov19 quarantine lol

[@DavidGurrney7589]

The best on the tube 👍👍👍👍👍

[@thomassylvestro9041]

your videos are always so good and detailed. I feel like I do anything after watching your vids

[@jmj267]

Can you look into that carb and show us a picture or a video of what actually that diaphragm look like. John small engine from Wisconsin

[@dujeamizic3588]

Aweson video

[@rk22cc]

can you do an old 011 saw carb replacement?

[@weldweld5629]

I know there was a o26 and 026 pro and I was told only the 026 pro has adjustable chain oil and decompression . Your thoughts on this ? Gotta carb setup video for this model??????

[@RussellBooth1977]

I've only had trouble with an aftermarket carby which I bought on EBay within Australia, it was a Walbro copy which I bought from someone whose based in Victoria. It was for a Stihl hedge trimmer that I rebuilt 2 years ago now & the main jet check valve was Loctited in,the fuel ate it away then it began to bog down the same as the chainsaw in the video,it had developed an air & fuel leak. I have had the same problem before with Welsh plugs that had been removed from them. My point is don't buy mower parts from a Muscat as I bought another carby which was from someone whose a bit more local (within 100 kilometres from me) on EBay for $30 AUD & the hedge trimmer went great after that. AFAIK the hedge trimmer is still going today !!!! Note that I've had no trouble with carbys which I bought from China for about 1/2 the price on EBay, in some cases,they need the throttle linkages from the old carby swapped over to the new one.

[@daniellibsfrant4866]

Por lo que veo en USA tienen las maquinas C , aqui en Argentina nos venden las comunes con 2 tuercas,me refiero al sistema de toma de la espada.

[@johnclarke6647]

I do not know what the exact carb bolt torque is for the MS 250 but the torque for the MS 440 is 2.5 FT LB or 3.0NM. I was surprised how low it was but I do know aluminum carbs will warp if tightened to tight. I usually tighten mine for 2-3 threads extending from the nut with a quarter inch nut driver. I think the key is equal torque on both nuts.

[@Patrick4959]

nice video and nice T-Shirt there Donny mate nothing beats a good Hot Wheels brand of it

[@dclawnmaintenanceandsnowre4099]

Nice video I like the shirt

[@rogerb649]

Thank you. What's your thoughts on the pre mixed fuel, such as True Fuel?

[@donyboy73]

it's good stuff

[@nagazinafireworks7594]

do you have a video on how to change a fuel line on the 250? or part #

[@jdubya54]

Doctor Dony. Put new engine and carb on stihl. Did about what you did on this saw. My arm is ready to fall off. can get it to kick and run for a few seconds on starting fluid. Tried all kinds of adjustments. I think it's not getting fuel. Put a new fuel line and filter. There is a fuel line coming off fuel tank with two brass threaded screws inside it. Like a breather hose. Took that off to make sure tank was breathing. Tried swapping old carb too. Any ideas. Also best starting spot for adjustment screws. Thanks

[@jerimahjohnson8698]

Need to do this to my mini boss

[@daphlavor]

Sthil should call it: ‘hard to start’, I’m going to bump the timing and increase the idle, on my ms250

[@splash5974]

Great vid as always! Question for you... My dad has a similiar saw, and hes been complaining that the saw is stalling alot, but only when its hot. Starts cold, idles fine, but after cutting for a little bit, you cant set the saw down and let it idle, because it stalls out. But works good other wise. Any idea what to look for? Thank you

[@splash5974]

Starts right back up, but only stays running with some throttle...

[@matthewvonnahme4235]

With that one being the easy start one does it have a primer bubble on it? I didn't see one.

[@smallenginekid6252]

The choke does work on mine did it exactly like u and it moves but Doesn’t move the carb choke

[@291zs]

Don, good video. Thank you. You say that the STIHL 1123-120-0620 is the proper replacement carburetor for the MS250 chainsaw. On eBay I found one with that number but it says it is for PRIMER SAWS ONLY. My saw does not have a primer bulb. Do you know what the proper part number is for my MS250? Thank you.

[@dougzabierek2309]

Donny Will food coloring damage the oil pump gear on a chainsaw when added to the bar and chain oil to see the oil come on the bar

[@donyboy73]

it shouldn't hurt

[@kenhosking3775]

I would like you to show me how to replace the pull cord on the ms250c it has stuff on the I'm not sure about

[@vinsvins6952]

Good day ! Why didn't you repair that carburetor? I mean the accelerator pump (which is under the air flap) or the membrane

[@ericcarter4344]

Hey there. I was wondering if sell parts for a ms250c? I have one and the starter recoil is broke and missing a few parts on the inside. I need the whole starter recoil assembly

[@jjparody8257]

You covered the pros & cons of OEM vs aftermarket but FWIW, OEM's are fetching $50+ online vs $12.99 (both US) for, get this, a carb, air filter, fuel filter, gasket, and spark arrestor. Both are made in China but maybe Stihl/Zama has higher quality standards. But possibly they both might be made in the same factory. Who knows?

[@billk5727]

Great video! What is causing the carburetor to run lean after the rebuild? Does it have a non- replacable hidden "o" ring inside?

[@donyboy73]

possibly permanently plugged or corroded in small passage ways inside

[@billk5727]

Ok.

[@Mihogan]

Hey Dony Boy, how do you know which Carb goes to the saw? I saw online that there are over a dozen versions of the MS250 carb... I can't seem to figure out which one I need and my dealer wasn't much help. I've got S92 620A stamped on the side of my original one, but googling that doesn't help.. any ideas?

[@KSMike1]

If you’re certain the problem is old gas & varnish, would it be worth running some Tru Fuel through it first (assuming it runs of course)?

[@588158]

if the carburetor has been cleaned and parts replaced what could be wrong with it? Could it be a warped throttle valve, warped carburetor body?

[@mattgardner4666]

I have a Stihl M250 chainsaw, can't get started. I replaced the carb. new fuel line and filter new spark plug and new gas tank vent. Any Ideas the plug has spark.

[@tylertotten890]

Can u change then over to a normal ms 250

[@alextim7645]

Air filter so dirty,or I mistakes? I changed diafragm on my carb only,works good.

Probably it's original color. :)

[@jayhiz3514]

Hey Donyboy, hkw do u deside to clean or just replace a carb? Is it based on hours of work vs cost of part?

[@donyboy73]

based on both, I usually always try cleaning and a carb kit, if that fails I replace

[@johnturner1453]

Why is there a spring inside the tank vent hose?

[@tnp_slay5814]

Donyboy73 are echo chainsaws any good.and would you recommend them.

[@donyboy73]

they are good but not as much horsepower as stihl or husqvarna

[@hitchensthinksnot4778]

I'm thinking the chain lock was the problem. Pull back on the hand guard and she'll run! Am I wrong?

[@paulhobbs6186]

what is the best way to get parts for the easy start recoil

[@donyboy73]

stihl dealer

[@oring137]

I replaced the carburetor, spark plug, new fuel and still will not start. I checked compression and it is good too. I'm thinking this is a donation and I'm going to buy a new chainsaw

[@jerrywhatsworth3589]

where does the black wire go it was just laying in the choke area??

[@rk22cc]

no gasket?

[@orkhancombe5]

hey Donny, do you ever work on M-tronic carbs from Stihl

[@donyboy73]

not too many

[@davidgaylord2035]

was it not worth it to clean the carb

[@Mihai1174]

the new and old carb are Walbro or Zama?

[@donyboy73]

both zama

[@TAKIOXELI]

how much did that carb cost?

[@mikeboggess255]

What exactly is wrong with the old carb.? You rebuilt it, yet it did not improve the saw's performance. I tried rebuilding cs carbs with not much success. I now simply replace them. So what goes wrong inside these carbs?

[@kilts4u2]

What kind of fuel are you putting into it? Any "standard" gasoline with ethanol is going to clog fuel ports and orifices. Learned that the hard way. I always use 100% "pure" gasoline. It costs more but the results are worth the price. Ethanol fuel is killing 2 and 4 cycle engines.

[@mikeboggess255]

OK got it. If you have been running eth. added fuel will switching to 100% gasoline unclog those passages?

[@kilts4u2]

Doubtful. You'll have to either clean those ports or replace the carburetor. Then, use ethanol free gasoline. Manufacturers and/or salesmen don't tell you this when you purchase 2 and 4 cycle engines. They should. It would save a lot of heartaches. Been there, felt that. Good luck.

[@TheOtherBill]

Stihl will tell you but nobody reads the manuals or even the handouts we gave out. If you use ethanol gas, stabilize it and don't use it after 60-90 days. Summer gas holds up longer than winter gas since it's not as volatile. Even pure gas needs to be stabilized unless you're using it all up this week. TruFuel or Moto-mix is a different story. They will hold up for a long time. I know Moto-mix is guaranteed for 2 years once the can is opened. Neither have alcohol. Those are the only things you should leave in the saw if you're not going to be using it for more than a month or two. The best over all but expensive, but it still may be cheaper in the long run if you only use the saw occasionally. The old gas has either clogged up the tiny passages or caused corrosion. The best cure is to not give it a chance by using it up before it goes bad, or not using it at all.

[@larrymunday7519]

The thing I have found wrong with those carbs when a rebuild kit has no effect is the o-ring on the accelerator pump. Yes, it has an accelerator pump. It is buried behind the throttle shaft and when the o-ring is bad it sucks too much air and will never run right. You can pull the little brass piston out and JB Weld it back in place. No more leaks or problems.

[@keithkamps77]

No gaskets?

[@Santiago-iv7oi]

👍👍👍👍👍👍👍👍

[@73superglide62]

Sounds like a plug CAT

[@bernardshelton7349]

Hip hip

But what exactly happened to carburetor? Did it clogged up?

[@donyboy73]

possibly permanently plugged or corroded in small passage ways inside

[@kilts4u2]

If you're using ethanol based gasoline, there's a good chance this is what's causing your carb to clog.

So it's always good to run Your small engine once in a while no matter of season.

[@kilts4u2]

I don't know where you're buying gasoline but I can get 100% ethanol free fuel at selected stations. I live in Tn. Not every locale has this.

[@kilts4u2]

Many of these stations are independently owned but you can also find chain outlets. In Tenn, we have stores called WEIGELS who always feature on pump at least that serves 100% ethanol free. I've found it at selected CONACO and PURE stations. I live in farm country and the demand for this fuel is high. On the other hand, I used to live in Atlanta and couldn't find ethanol free gas anywhere except at one fuel company who only sold it by the gallon. You couldn't put it into your personal vehicles. Personally I feel that oil companies collude on this.