Stihl MS171 stalls when I throttle?

[sika]

Sorry team, I have another problem.

Mate gave me his near new MS171. Was working, didn't use it for a month, then when he went to use it again it wouldn't throttle. Pull throttle and it will die and stall.

Being I am now a guru at pulling apart carbs, this is what I did. Inlet needle cleaned etc etc.

New fuel - check
Cleaned the pug - check.

No difference.

Air filter etc is clean as - even without air filter on, same.

Took chain and bar off, same.

Re set the carb adjustment srcews, L - out 3.4 turn, H - out full turn. Same.

Thought it might be the tank breather so I took the cap off the tank and ran it. Same thing.

I will try and get a video up. In breif but, starts easy, just when I pull throttle it dies and stalls eventually.

Most post head towards cleaning the carb... again and again. Its like a diamond in there now.

Ideas?

 

[welderboyjk]

Can you put your finger partially over the carb inlet and "choke" it while you try and rev it?
If that helps then you've hot a fuel problem I'd think. If it doesn't then I'd look elsewhere.
Fuel filter
Fuel line I'm sure there's probably an impulse line somewhere too
Bad diaphragm in the carb
Maybe a plugged spark arrestor screen

Good luck

 

[ckelp]

Your carb claped out you need a new one
If my memory is correct replace it with a wally 215
You'd just have to trim some plastic to adjust the carb
I jist did a 017 the owner said that saw never ran soo good

 

[bluestripes]

Did you check the spark arrestor screen?

 

[watsonr]

It sounds like it needs a carb kit. If the choke thing works and it runs while the opening is partially closed by your finger.. you need a carb kit. Or you can bottle feed it fuel and it runs fine... carb kit.

 

[blsnelling]

Your carb claped out you need a new one
If my memory is correct replace it with a wally 215
You'd just have to trim some plastic to adjust the carb
I jist did a 017 the owner said that saw never ran soo good

This is a 171, not a 170.

 

[sika]

Did you check the spark arrestor screen?

No, haven't tried that one yet.

Man, these carbs must be crap, my 029 will run on diesel almost and starts everytime after storage and it is over 15 years old!!

Will try the arrestor side.

 

[Sprint60]

Chain brake?

Not trying to be a jerk, but its the kind of thing I'd do: forget to check the brake is off. That's exactly how my 260 behaves when it's cold and I forgot to disengage the brake. You know, kick-your-self-obvious.

 

[moody]

Not trying to be a jerk, but its the kind of thing I'd do: forget to check the brake is off. That's exactly how my 260 behaves when it's cold and I forgot to disengage the brake. You know, kick-your-self-obvious.

Where at in MO do you live?

And to the OP I'd say vaccuum test the saw. It could be crank seals, or the carb as you've state, it could be bad impulse. Lot's of thing's it could be, vac and compression test's will eliminate a lot of things.

 

[BloodOnTheIce]

Once the 171/181/211's break in they need to richened up.

Somewhere between a 1 1/8 and 1 1/4 turns on the low and back out the high to hit the limite
is usually what they need.

 

[sika]

*** fixed ***

Did you check the spark arrestor screen?

Thanks again guys!!

This was the problem. Slipped out the little piece of gauze and I couldn't see thru it! Quick clean, slipped back in... boom.. back in action.

 

[Boydt8]

my 2 cents

Well I had a same problem, it was a bad Diaghram... Then a month later did it again, this time it was the screen in the muffler, it was clogged.
Also Id stick to a brand name saw mix, Shihl or Husky brand.
Reason I say that is one time I bought a saw mix that was not brand name, it keep clogging up my muffler screen, then change to stihl gas mix, never happended again.