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Stihl MS460 wont start
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Posted by
raydecker (
My Page) on
Mon, Aug 22, 11 at 18:26
| 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 |
Follow-Up Postings:
RE: Stihl MS460 wont start
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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. |
RE: Stihl MS460 wont start
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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 |
RE: Stihl MS460 wont start
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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 . |
RE: Stihl MS460 wont start
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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 |
RE: Stihl MS460 wont start
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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.
Thanks |
RE: Stihl MS460 wont start
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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. |
RE: Stihl MS460 wont start
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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 |
RE: Stihl MS460 wont start
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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. |
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