Stihl MS170 Issues

[DaveJr.]

Hello all!

I am about ready to give up here. Have a Stihl MS170 that is giving me issues. It will start up and run at full throttle right as it turns over but as soon as I release the throttle it will die. Will not idle at all. If I release the throttle, let the RPMs come down and give it more gas, it'll struggle to get back up to full revs. It seems to always need one or two pulls on full choke, and 3 pulls on half choke will start and rev up. I have read just about every forum post on similar issues and have had no luck. The saw doesn't have much use on it but is at least 6+ years old (Dad bought it back then). New plug, fresh gas mix, cleaned the carb, spark arrestor is clean. I'm not great with small engines, have only really done basic repairs, but I am dumbfounded here.

I really don't want to have to bring it to a shop as this saw is less then $200 new. If anyone has any suggestions, it would be greatly appreciated. 

[axeman2021]

Hello all!

I am about ready to give up here. Have a Stihl MS170 that is giving me issues. It will start up and run at full throttle right as it turns over but as soon as I release the throttle it will die. Will not idle at all. If I release the throttle, let the RPMs come down and give it more gas, it'll struggle to get back up to full revs. It seems to always need one or two pulls on full choke, and 3 pulls on half choke will start and rev up. I have read just about every forum post on similar issues and have had no luck. The saw doesn't have much use on it but is at least 6+ years old (Dad bought it back then). New plug, fresh gas mix, cleaned the carb, spark arrestor is clean. I'm not great with small engines, have only really done basic repairs, but I am dumbfounded here.

I really don't want to have to bring it to a shop as this saw is less then $200 new. If anyone has any suggestions, it would be greatly appreciated.

My best guess it has to be a problem with the carb.

[Tacotodd]

Sounds like a MASSIVE vacuum leak (to me).

I'm curious though what you find out.  smiley_confused  smiley_heh_heh 

[Hickory Bow]

I am thinking fuel filter, but you also did not mention cleaning the air filter...Both of those are easy fixes if that is your problem...

[DaveJr.]

I am thinking fuel filter, but you also did not mention cleaning the air filter...Both of those are easy fixes if that is your problem...

Yup, forgot to mention those, checked both and they are good as well

[Fishnuts2]

Check the fuel inlet screen in the carburetor.

[MakitaDolmar]

(EDIT: didn't know 170 carb had 1 screw)

[Michael]

Hey new guy have you ever worked on a 017 or ms170? Unless it is a really old saw the carb does not have two screws and the one screw model is a left hand thread.

[sablatnic]

Could be your pulse line having
 cracked