Help with odd Stihl Problems.

[MCNY]

I would like to start by saying thanks to everyone for the great information on this site. It has helped Me sort through many problems.
I have been having a very strange problem with multiple Stihl saws from 024's to 084's. I have puchased no less than 6 stihl saws either locally or off ebay. The local saws ran good when i tested them prior to purchase and the ones from out of state either required a little carb adjustment or ran fine for anywhere from a few minutes to several hours. They all ended up getting to the point where they would start and run for a very short time and stall acting like they are running out of gas. I would figure it was the fuel i am using except I have a 029 that I have had since it was new and a 020 av that i picked up that both run great with the same fuel. I have also had a couple other saws that didn't have any trouble or ran fine after some carb adjustment. I am using Stihl 50:1 and super unleaded. I have rebuilt the carb on a 036 still won't run right. I have a 026 that ran like a dream for several tanks and now I can't get it to run more than 30 seconds. I can't beleive they all have developed bad seals or fuel lines. Any suggestions would be appreciated. Thanks.

 

[wigglesworth]

The only common denominator is the fuel. With them starting for a little bit and then running crapping out, makes it sound like they have low compression. I would say a compression test is in order. Hopefully you didnt fry several saws.

 

[stihlboy]

check your fuel filters

 

[MotorSeven]

Like Wig said....fuel, specificly....ethanol. Try AV gas or race fuel & see if their is a change. How old is the fuel in you saws? The days of firing them up after sitting full of gas for a year are long gone.

RD

 

[SteveG]

I can't beleive they all have developed bad seals or fuel lines. Any suggestions would be appreciated. Thanks.

The symptoms you describe, stalling after running for a while, was what I was experiencing on my older 028. Several people here gave me ideas and suggestions but my problem still existed. I finally took it to a Stihl dealer several cities away to see what they could find (my local guy gave up). I had tried new fuel, fuel filter, vent line & carb adjustment. They ruled out the coil and gas and after talking to their "guy" in Dallas determined it was something in my lower "jug" was causing vacuum loss after the engine warmed up thereby causing the carb to fail due to lack of vacuum. Because my saw is so old and parts are hard to get I'm to the point of buying a new 361. My 028 will run about 20 minutes and then start starving for fuel. I can let it cool overnight and run it again for 20 minutes or so. The one thing that I still have problem with is these symptoms didn't start until after I replaced the fuel tank / handle assembly with an old 028 Super. But after changing all the hoses, line, fuel filter and switching carbs, I'm assuming the dealer is correct.

 

[GASoline71]

Carb rebuilds... if they've been sittin' for a long time... could have gummed up diaphrams...

Gary

 

[fredmc]

Check the tank vent, it's the tube with the set screw in it. I've had to replace nearly all of the vents on the stihls I bought that have sat. Stihl's vent tube gets hard and I don't think it works right after a while. I always replace the vent tube on any Stihl builds I do.

 

[MCNY]

Thanks for all the suggestions. I figure it has to be fuel related because as someone said it is the only common denominator. I have checked compression cold on all the saws and they all have ranged from 150-180 cold after 6-10 pulls, I have pulled the vent tubes right off the saw to try and eliminate that issue. I have changed fuel filters, tried without fuel filters, rebuilt carbs.all with no luck. I am running super unleaded. Does it still have ethanol in it? And if it is the fuel why does the 029 and the020 run perfect. (The 020 AV is like a Rottweiler in a poodles skin). One carb i took apart had almost like a milky gel build up in the screen inside. Does the ethanol damage rubber? My most recent victim is an 026 that ran great for several hours and has 180 lbs compression. I changed the clutch springs and can't get it to run worth a darn. It has the intellicarb on it and i have read the posts about them so i have purchased a replacement carb and will put that on soon. Is there an additive I can put in the gas to reverse the effects of the ethanol? Maybe I just need to find another hobby. Thanks Again!

 

[sefh3]

Just a thought but what kind of oil are you using?

 

[ms290]

1 OZ. of MMO (Marvels Mystery Oil) in with your fuel to supplement your fuel mix itself. Keeps that damn ethanol from eating it up quite so bad

 

[SawTroll]

Check the tank vent, it's the tube with the set screw in it. I've had to replace nearly all of the vents on the stihls I bought that have sat. Stihl's vent tube gets hard and I don't think it works right after a while. I always replace the vent tube on any Stihl builds I do.

I was thinking tank vents as well.

It is easy to derermine - open the gas cap and retighten when it starts acting up - if it runs right for a while after that, before acting up again, it is the tank vent.

Another way is to run it with a semi-loose gas cap (that isn't air tight), and see if it helps.

 

[Fish]

Actually, the other common denominator would be that they are all Stihl saws.

If it was a Husky, I'll bet it woukl still be running...........................
















But likely, you will need to get fresh fuel and rebuild the carbs, clean out the nasty fuel varnish..

 

[Fish]

How was that, Sawtroll?

 

[Mastermind]

cold fish, lol

 

[chad3]

Had the issue with a 361, wasn't sure if it was a filter or breather. Swapped out the breather and cutting again in about 10 minutes.
Check it.