troubleshooting help stihl 260

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dgdm

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Hello, first post here, I have been searching the forums diligently for some time though to try and find a solution... My stihl 260 was running fine one day, next day it would hardly start, wouldnt idle, if I held the throttle open it would surge up and then die, sounded like it flooded, when it caught for a few seconds it would seem to run strong but then it would die, was very hard to start. I tried new gas, new carb, new fuel and impulse lines all with no luck. I have tried with and without muffler on, have cleaned air filter, I have inspected the piston, rings and cylinder wall, all seem fine. spark plug sparks, has very good compression. the other day I picked up a used 260 for cheap and swapped out the carbs, old saws carb in the new saw runs fine, new saws carb in the old saw = same problem.

I am running out of ideas. I am down to suspecting something electrical (even though it sparks, maybe something more happening) or something in terms of vaccum. any ideas on where to go next? on the plus side I have learned alot about saws trying to figure this out.
thanks
David
 
pioneerguy600

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Hello, first post here, I have been searching the forums diligently for some time though to try and find a solution... My stihl 260 was running fine one day, next day it would hardly start, wouldnt idle, if I held the throttle open it would surge up and then die, sounded like it flooded, when it caught for a few seconds it would seem to run strong but then it would die, was very hard to start. I tried new gas, new carb, new fuel and impulse lines all with no luck. I have tried with and without muffler on, have cleaned air filter, I have inspected the piston, rings and cylinder wall, all seem fine. spark plug sparks, has very good compression. the other day I picked up a used 260 for cheap and swapped out the carbs, old saws carb in the new saw runs fine, new saws carb in the old saw = same problem.

I am running out of ideas. I am down to suspecting something electrical (even though it sparks, maybe something more happening) or something in terms of vaccum. any ideas on where to go next? on the plus side I have learned alot about saws trying to figure this out.
thanks
David
Did I read wrong or did the carb off the parts saw work fine on your existing saw?
 
SteveSr

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Hello, first post here, I have been searching the forums diligently for some time though to try and find a solution... My stihl 260 was running fine one day, next day it would hardly start, wouldnt idle, if I held the throttle open it would surge up and then die, sounded like it flooded, when it caught for a few seconds it would seem to run strong but then it would die, was very hard to start. I tried new gas, new carb, new fuel and impulse lines all with no luck. I have tried with and without muffler on, have cleaned air filter, I have inspected the piston, rings and cylinder wall, all seem fine. spark plug sparks, has very good compression. the other day I picked up a used 260 for cheap and swapped out the carbs, old saws carb in the new saw runs fine, new saws carb in the old saw = same problem.

I am running out of ideas. I am down to suspecting something electrical (even though it sparks, maybe something more happening) or something in terms of vaccum. any ideas on where to go next? on the plus side I have learned alot about saws trying to figure this out.
thanks
David
Put up some pics of the piston viewed through the exhaust port.
 
atpchas
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I am running out of ideas. I am down to suspecting something electrical (even though it sparks, maybe something more happening) or something in terms of vaccum. any ideas on where to go next?
It is possible that one or both crank seals have let go or a gasket is leaking. Suggest you do a pressure/vacuum test before pulling out much more hair (assuming you have any to pull - mine is long gone).
 
thenne1713

thenne1713

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Hello, first post here, I have been searching the forums diligently for some time though to try and find a solution... My stihl 260 was running fine one day, next day it would hardly start, wouldnt idle, if I held the throttle open it would surge up and then die, sounded like it flooded, when it caught for a few seconds it would seem to run strong but then it would die, was very hard to start. I tried new gas, new carb, new fuel and impulse lines all with no luck. I have tried with and without muffler on, have cleaned air filter, I have inspected the piston, rings and cylinder wall, all seem fine. spark plug sparks, has very good compression. the other day I picked up a used 260 for cheap and swapped out the carbs, old saws carb in the new saw runs fine, new saws carb in the old saw = same problem.fuel line inside the tank and the FUEL FILTER

I am running out of ideas. I am down to suspecting something electrical (even though it sparks, maybe something more happening) or something in terms of vaccum. any ideas on where to go next? on the plus side I have learned alot about saws trying to figure this out.
thanks
David
CHECK COMPRESSION? Husqvarna says theirs will not run below 120-psi. A Stuck/ sticky ring can give 90 and FEEL good. If you did all you did correctly, did you replace FUEL LINE INSIDE the tank, and/ OR CHECK/ AND FUEL FILTER? If all that is good, may need vacuum/ pressure test w/ sock of crankcase to check crank SEALS/ GASKETS?
 

dgdm

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thanks the piston and rings look very good much better than they do on the 340 I have which runs fine but has low compression. I also, carefully with a small screwdriver, confirmed that the rings are not seized, they are springy in the piston grooves. Also, from pulling the cord I would say the compression on this saw is very high, always has been, much harder to pull than the 340, the 290, or the parts 260. I think i need to look at the vacuum side of things, which I don't have the equipment to test. I have seen a youtube video on pressure testing lower end, it will be a bit of an investment to get that gear, I may be easier to bring it to a shop to have it tested than buying what would hopefully be a one time use.

thank you.
 

dgdm

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thanks the piston and rings look very good much better than they do on the 340 I have which runs fine but has low compression. I also, carefully with a small screwdriver, confirmed that the rings are not seized, they are springy in the piston grooves. Also, from pulling the cord I would say the compression on this saw is very high, always has been, much harder to pull than the 340, the 290, or the parts 260. I think i need to look at the vacuum side of things, which I don't have the equipment to test. I have seen a youtube video on pressure testing lower end, it will be a bit of an investment to get that gear, I may be easier to bring it to a shop to have it tested than buying what would hopefully be a one time use.

thank you.
and yes, I replace fuel line inside of tank and the impulse line
 
Wise Guy

Wise Guy

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I had a similar problem with a Poulon. I spent endless hours on it. A spark plug was the last I changed and fixed it.

Even though a spark plug can throw a nice fat spark when unscrewed, under compression it may fail and this is what happened. Change the spark plug.
 

Lnk

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I had a similar problem with a Poulon. I spent endless hours on it. A spark plug was the last I changed and fixed it.

Even though a spark plug can throw a nice fat spark when unscrewed, under compression it may fail and this is what happened. Change the spark plug.
Beat me to it. Swap plugs between the two saws.
 

dgdm

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well, you were close, I did swap the plugs and didnt fix it. but, .I am happy to report that I swapped the ignition coil out and it started right up and ran strong. The spark that I was getting was too weak, the wire had a bad spot on it and the coil from parts saw fixed all the problems. thanks for all the ideas, they were helpful. I was thinking it was the vacuum but this is much easier, i now need to decide to get and OEM coil or aftermarket.

on another note, when trying to check the vacuum I was going to try a simpler option of spraying some ether near the seals to see if it would start running stronger, a mechanic told me that this is how they used to test the snowmobiles. I never got to try it as it would no longer start at all.

thanks again
David.

Next topic is going to have to be which saws should I sell and which should i keep. I think I should sell one of my 260's and my 290, keep my 340 and maybe upgrade it to a 360 and consider buying a larger saw 400 or 440/460 class. I only use my saws for firewood but I burn about 4 bush cord a year and might want to do a bit of milling if I had a saw that was suitable for a small amount of milling, i already have a small chainsaw mill but dont have a saw well suited to it.
 
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