Stihl MS460 wont start

raydeckerAugust 22, 2011

Hello all, I'm working a Stihl MS460 chainsaw that will not even attempt to fire. Compression is 80 psi on one (1) pull. There is a good blueish color spark. I have changed the fuel & spark plug. I have even tried spraying starting fluid both in the carb & cylinder, still nothing. Even pulled the flywheel thinking that maybe its out of time but the keyway was good. I had the carburetor off & when looking into the intake at the piston that is retracted to the all the way down posistion (reverse of tdc) there is only about 1/16th" space for the fuel to enter the cylinder. This to me dosent seem like enough space for fuel to get into the cylinder. Also now I'm thinking now that 80 psi is not enough compression. thanks for any help. Ray

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Ray: Your correct in that 80 psi is not sufficient , either though is one pull . Remove the spark plug and spray a little wd-40 or 1/2 ounce of sae 30 oil down the cylinder. Then pull the recoil over 3-4 times. After this you can retry your compression test , 4-5 pulls is req'd for a accurate test. You should achieve 130 to 160 psi to have a optimal performing unit. Let us know how it goes. Should you see less than 100psi I would think you have a frozen (seized) ring or perhaps worn beyond spec.

    Bookmark   August 23, 2011 at 1:15PM
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Thanks for reply ewalk, did as you instructed and sprayed wd-40 into cylinder & checked compresion. It was 140 psi with 5 pulls. So I removed compression gauge & sprayed a little more wd-40 in cylinder, replaced plug & it fired on the 2nd pull but would run. So now I sprayed some into the carb & it started right up and stays running on its own. I have started it a half a dozen times so far & it starts every time. This saw belongs to our local fire dept where I work. It has a shroud around the bar & chain witch allows them to adjust the cutting depth when they have to remove the roof sheeting to gain access to a fire. First time I have seen this type of set up. Thanks for your help again ewalk, Ray

    Bookmark   August 23, 2011 at 5:02PM
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No problem Ray , glad to be of assistance . You may wish to utilize some fuel conditioner for storage protection , since the saw may sit for an extended period between ussage .

    Bookmark   August 23, 2011 at 10:18PM
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I am encountering a similar issue where when following the starting procedure neither of our MS460 Rescue saws will start. I am a long time user of 2 stroke products and usually pull with choke, tries to start, take choke off fires up and lets get to work. These saws have had this issue since they were bought. We are using the 50:1 SEF synthetic fuel. I have not tried teh WD40 in carb becuase these saws are like new even though they are 3yrs old and should not need this, I will try it later this evening though to see if it makes a difference.. Any ideas ? I am ready to chunk them and switch back to husky or jonsered based ventilation chainsaws.
Stay safe

    Bookmark   December 6, 2012 at 12:47PM
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In regard to previous post, our issue appears to be too much fuel and a wet flooded plug, every time regardless of choking or just pulling with no choke.

    Bookmark   December 6, 2012 at 1:02PM
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I would believe that the inlet needle valve within the carb under the diaphram is sticking open causing the flooding condition.

    Bookmark   December 7, 2012 at 6:39PM
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Thanks Ewalk,
We are getting a bit more consistency with one pull full choke, 2-4 pulls half choke then on burp, going to no choke. It is not flood free but at least we get the saw started. Should all of our Stihls be looked at or leaned up to run the SEF 50:1 fuel? The dealer knew we were going with the synthetic fuel from the onset, it is driving me nuts when trying to get these units to run. We have got to get these units to starting on about the 4-6th pull every time by any trained person assigned to the seat. We have 5 units that have at max probably 20hrs run time on them but if I had my choice I would trade em all for other manufactures as a result of our experience over the last few years. This would never have crossed my mind prior to purchase as I have had stihl products for over 30 yrs with NO starting issues.

Stay safe.
Capt. Nelson

    Bookmark   December 11, 2012 at 11:45AM
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Your Stihls are fine units . I run Huskys and Stihl all within 4-5 yrs vintage. The Stihls are Epa lean starting units . Some times rejetting is required to improve the 1 or two pull starts . Normal is 4-5 pulls on a stock unit unfortunately . You have not mentioned your fuel is it ethanol blend . If so a conditioner such as Star*tron available at Walmart or Napa is very important to provide trouble free fuel and saw performance. I usually recommend Amsoil Sabre full synthethic oil which is recommended at 50:1 by all Dealers. Try running a full fuel load with either lucas top end conditioner or Star*tron which should clean up our fuel circuits . If you have not inspected your fuel filter do so prior and also inspect your inlet needle valve for free movement as previously suggested . These saws should not flood if the carbs are clean . Quite often saws which are stored for prolonged periods without fuel conditioner have this type of flooding condition.

    Bookmark   December 12, 2012 at 3:49PM
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I just bought a Stihl 250 and had a devil of a time getting it started. I was trying to start it today and no joy. Out of desperation, I decided to take it back to the dealer. When I got to the store, I decided to do a search on my Droid and came across this video and watched it on my phone, right in the parking lot. I got the saw out of my trunk, followed the advice in this vid, and it started right up! Fantastic!

Here is a link that might be useful: Start a flooded engine

    Bookmark   August 6, 2013 at 3:04PM
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I bought a used MS 460 a couple of months ago and didn't have any trouble starting it until the last couple of weekends when I couldn't get it to fire. The MS 460 was significantly larger than any saw I had used before and the first saw I had used that had a compression release. The compression release and the video SammyQ2 included in his comment above helped me dry my saw out and get it started.

My saw also produces 80 psi on the first pull like raydecker's saw and I think that is plenty high enough at the head on the first pull if the crackcase seals are holding there pressure correctly. After several pulls my saw maintains 150 psi.

What I figured out by studying my spark plug while it was out of the saw was that the compression release on these larger saws is more than a convenience and at times can be very important for getting a high RPM crank that will create an intense spark that can jump a wet spark plug. When I was having trouble getting the saw started I hadn't been using the compression release at all. As soon as I started using the compression release correctly, pressing it before the first pull and after each "burp", the saw started.

Here is a link that might be useful: How to fix a flooded motor

This post was edited by YardArtist on Wed, Sep 4, 13 at 16:28

    Bookmark   September 3, 2013 at 5:35PM
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Hello Ewalk, since the early 70s we were encouraged to use oil in the cylinders of old cars that had been sitting for years (that ran) to increase the compression to start them.

Personally, I start my extra equipment that is not used in 4-6 months with fresh fuel and Stabl or Etc treated fuel to ensure it will be ready if needed.

Knowing the issues, I feel starting every 4-6 months or sooner would be required of Emergency Units with treated fuel and suggested to all. Such as, itâÂÂs time to fire up the Gas Log Splitters and my 110V Electric I like to use below 70 degrees. The bottom Line Is, you have to respect and understand equipment vs just using it.

    Bookmark   September 3, 2013 at 8:46PM
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Loger: Your absolutely correct any 1st response equipment should be tested at predetermined frequencies , monthly at the very least . Also fuel treatment would be mandatory to ensure quick response within emerg. situations. As for decompression usage , I hardly ever used mine on my 460 Husky and it starts on second pull every time. I still believe the hard starting with the stihls is carburation issues.

    Bookmark   September 4, 2013 at 4:17PM
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ewalk: I would be hesitant to compare the starting characteristic of the Husky 460 to the Stihl MS 460. The Husky 460 is 60 cc; MS 460 is 76cc.

While the Stihl has 26% more cc's, it uses the extra cc's to produce 66% more HP, 6.0 HP, as compared to the Husky's 3.6 HP. I suspect the Stihl has a higher compression ratio in addition to the higher displacement. At times it pulls the starting rope out of my hand which really smarts despite the extra rubbery starter pull.

My Stihl MS 460 is a very fast saw for its displacement. I can bury the 28" bar in White Oak and it cuts it like Aspen. Husky makes some large saws that are faster than the big Stihls, but the Husky 460 is more of a retail saw that isn't really in the professional class.

This post was edited by YardArtist on Thu, Sep 5, 13 at 10:27

    Bookmark   September 4, 2013 at 5:36PM
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YardArtist: Your correct within the saw specifications. However this does not affect a change within the starting of the Husky and Sthil Saws. I routinely start my Vintage Pioneer 550 (95 cc) with 1 prime pull / full choke and light it up with the second pull religiously . No decompression release on this Old Girl or required for this 63 yr old youngster lol.
Anyhow have been cutting and repairing saws for over 40 yrs and own numerous Stihl / Husky / Pioneer and Dolmar Saws . Seen the Good , Bad , and Downright Ugly .

P.S. The Decompression Release reference within the Sammys advised video was within allowing purging of excess fuel within a flooded unit (remember a engine is primarily an air pump) and to assist novice operators easily within proper starting procedures. The cause of the OP 1st post issues was fuel starvation and secondary flooding due to a fouled carburator , due to sour fuel . I will have to remind my Brother to ensure he uses his decompression on his MS 660 Magnum next week when we finish our fall firewood cutting ...Yah... Right Roflmbo :)

    Bookmark   September 4, 2013 at 8:25PM
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YardArtist: Don,t understand why you felt required to edit your previous note rather than continue your contributions in a new note.
Anyhow yes my 460 Rancher is a Prosumer Grade Saw . Your Stihl 460 along with my current Stihl MS-250 and MS 361 and Husky XP-346 and Dolmar PS-9000 are Pro Grade Saws. They do produce considerable more Peak Horse power within a higher rpm range with a nominal higher compression ratio , than does the Rancher which is more of a Torque Driven Middle Weight . However neither one of my saws with or without decompression usage fail to start within 1or two pulls. Even as previously advised my Old Pioneer 90 cc or my New Dolamar 88 cc both with 36 inch bars that routinely cut Red Oak and Canadian Maple like Butter. The most I use the decompression feature on any of my saws is to quickly purge the fuel charge , rather than to have to remove the spark plug when the saw has become flooded , which is very seldom. I realize that some owners as you have advised have little experience within saw dynamics therefore rely on video's to understand proper starting techniques . Not a bad idea since all saws are unique . However the issue with all my Stihls today and 3 yrs ago is EPA (lean burn) Carburation which in some cases due to elevation even requires rejetting . Like I said previously proper saw storage and fuel treatment during said storage is the Key ! As a Newbie to the Forum Welcome aboard and Happy Cutting ! I will be sure to advise you when this 60+ Old-Timer requires the Decompression Button to start any of my units Possibly next week when I finish my last 10 cords :)

    Bookmark   September 5, 2013 at 3:22PM
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Ewalk, Good Timing! I finished my major harvesting from the curbs in May beating the TX Heat. I have gotten calls and gotten small ü cords approx 4 since the major loads. One lady called to let me know they were having a live Red Oak removed since she remembered I took a load of the first removed. I d/n have room for a stick of wood but thanked her. Pecan #1 and Red Oak #2 are the dominate trees being removed in our Old Neighborhood due to size vs dead. 6âÂÂ-12â Dia, 16âÂÂ- 24 â long is my size goal.

My major concern now is getting seasoned dead wood off the curb due to it possibly having beetled that could get into our 4 live trees. We have A 40 yr old Live Oak and Pecan that my wife planted in 1973 when we moved in. I do know we have lost an Apple and Red Oak to beetles. My recent goal is to bring home green wood. BUT! I can cut healthy green standing Mesquite, bring home and bores will have dust coming from it before itâÂÂs seasoned. I have seen one borer (attached) that looks similar to the Asian borer from China. I guess we have bores Regardless?

60 + yrs and 10 years of retirement slowed me but IâÂÂll Challenge most my age or younger to Whatever!!

    Bookmark   September 5, 2013 at 9:27PM
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Loger great to hear that you have found suitable firewood for your needs. Unfortnuate within the Asian Beetle Infestation. Does your Local or State Authorities have a plan for spraying or other plan to attack these evasive beetles ? We had a situation back in the 80's with Dutch Elm Disease . Pretty well killed the majority of mature trees within the central part of the city . Fortunately no other tree species were affected and herbicide was used to successfully control the outbreak. As for me , getting ready for Bow Season for Deer and have to finish off the firewood cutting and splitting . Have approx. 7 cords of Canadian Maple cut and split and another 2-3 cords of White and Silver Birch left to cut this week . Had a couple of days of light frost so the cutting and splitting sessions have gone well . Well you take care good hearing from you again Old-Timer lol.

    Bookmark   September 7, 2013 at 10:30AM
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Asian Long Horned Beetle info at the bottom X 2, Lazy me!

Ewalk And All, I sent this 1st attachment to my County Extension Agency and it was not thought to be an Asian Long Horned Beetle. IâÂÂm almost sure I saw this 1st beetle a few years ago and thought it was a Yellow Jacket Wasp. The beetle was too slow and clumsy to be a Yellow Jacket Wasp. I feel with firewood you'll have some types of beetles or bugs. Opinions! Most seasons since the late 70s I was able to store 5-7 logs inside due to not openly seeing bugs.

The varieties of beetles I have seen the last few years are becoming a bigger concern. As I mentioned I will plan to harvest only green wood in the future from trees being trimmed or removed vs dead. You would not believe the number and size of trees on our small 120â D X 70â W lots (mine included with 5 trees, 2 are 40 yrs old. The neighborhood is approx 50 yrs old. I have personally trimmed ours the last time above a groundâÂÂs reach vs the Utility Co and Trimmers.

Attached is what an Asian Long Horned Beetle appears as (similar to what I saw).

PS. I need to start a post on the Long Horned Beetles but more than one easy attachment influenced this move.

    Bookmark   September 7, 2013 at 5:13PM
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