Stihl MS 170

[emr]

Don't laugh but I am having a problem with our 170 and I am not sure whats going on. The saw is basically new and its acting up when we throttle it all the way up. It seems to start a little rough but it will start and run at idle. I can throttle it up to about 3/4 and it seems to run fine but if I pull the throttle all the way open it will die off. Any suggestions on what to do?

 

[wiley_p]

Sounds like you are rich on the high end. Is your air filter clean/dry?

 

[emr]

Air filter is clean. The carb on that saw only has a LA screw and I tinkered with that and it made no difference. I am not very well versed in chainsaw workings but this just seems like it should be an easy quick fix.

 

[Monkeywithasaw]

seal in the carb not seated all the way

 

[CurSedVoyce]

Check your spark arrestor and muffler as well. Little bugger clogs pretty easy.

 

[emr]

Will do. We really haven't used it that much. I would be surprised if it was dirty but it's worth a shot. We are also going to change out the fuel just in case it went bad.

 

[Al Smith]

What it could be happening sounds like one of two things .If the fuel shut off lever is set too low it won't fill the fuel chamber completely up and at full throttle you're actually over running the carb .It could possibley be the diaphragm has gotten stiff and that will give the same symptoms .

If the saw is as new as you say though it wouldn't make sense the diaphragm stiffened up already but I suppose it's possible .Oh too a stiff or mis set diaphragm will make them hard to start also .You have to pull them a zillion times to get fuel to the carb .

 

[greatoutdoors]

You have a fuel problem and if the saw isn't too old, just take it back to the dealer and have them sort it out via warranty. I imagine your carb is a little gummed up or just plain junk. If those fix jet carbs aren't close to perfect, it hell to get them straight. I usually just find another one.

 

[emr]

I just picked up our saw from the Stihl dealer. They replaced the carb and the fuel line. They blamed it on the fuel. I had some interesting talks with the mechanic about ethanol, synthetic oil, and all that good stuff. I have to admit I picked up a can of that Fuel50 to tryout. I am not holding my breath but we will see how it works.

 

[Al Smith]

I won't think ethanol in the fuel would screw it up that fast .No matter,they fixed it .

 

[emr]

That's what I thought too but like you said they fixed it for free so who cares.