Issues with stihl ms171

[StaggerLee13]

I'm still pretty new to this forum so forgive me if this topic has already been discussed but I'm having issues getting my little ms171 running. I thoroughly cleaned and rebuilt the carb, replaced the fuel lines and filter, and removed the spark arrester and it still won't run. It starts and idles but as soon as I give it gas it falls on it's face and dies. If anyone has any advice, possibly a manual, I'd greatly appreciate it.

Thanks, StaggerLee.

 

[Shane¹]

Sounds like might still have a carburetor issue. Could be dirty or just out of adjustment try turning low needle out a little

 

[StaggerLee13]

I've done all of that. Cleaned it thoroughly, rebuilt the carb using the zama rebuild kit. Replaced the fuel lines and filter. Thought it might be a clogged spark arrester so I took it out, it was definitely dirty but I could see through it. I removed it anyways and still having issues.

 

[Woodwackr]

Fuel starved, most likely.
Oe replacement fuel line or aftermarket? Check the new line for a soft spot that can collapse when throttle is engaged...common with AM.
Recheck the filter...if you had a lot of crap in the tank it could already be clogged...or was bad to begin with. Can you blow air through it?
Pull the muffler and see if you have excess carbon buildup in the muffler or port.

 

[Brad Button]

Put a new carb on it. If the 171 is anything like the 170/180 those carbs rarely clean up and take a carb kit. I just looked at the IPL and that carb has hi/lo jets, have you pulled the limiter cap and tried richening it up?

 

[Sloughfoot]

Over 18 years, 4 separate things caused my little 180 to not run well. Clogged spark arrestor, filter cover hindering throttle linkage, fuel filter, carburetor.

When it was the carburetor a rebuild didn't fix it, new carb did.

 

[bogieboy]

Put a new carb on it. If the 171 is anything like the 170/180 those carbs rarely clean up and take a carb kit. I just looked at the IPL and that carb has hi/lo jets, have you pulled the limiter cap and tried richening it up?

This.... carbs are cheap enough for these, they arent worth the time to rebuild...

 

[StaggerLee13]

Put a new carb on it. If the 171 is anything like the 170/180 those carbs rarely clean up and take a carb kit. I just looked at the IPL and that carb has hi/lo jets, have you pulled the limiter cap and tried richening it up?

Yeah, I removed the limiter caps and tried to richen it up but to no avail. I tore the carb down a second time and cleaned it thoroughly and it seems to have made some difference but still bogs and dies when I open it up. A new carb is pretty much where I'm at with it at this point.

 

[StaggerLee13]

Over 18 years, 4 separate things caused my little 180 to not run well. Clogged spark arrestor, filter cover hindering throttle linkage, fuel filter, carburetor.

When it was the carburetor a rebuild didn't fix it, new carb did.

Yeah, that's where I've landed with the situation. A new carb it is.

 

[Woodwackr]

Have done several 170s with carb issues. each one did fine after disassembling and sonic tank in carb cleaner. Didn't even need kits.

 

[StaggerLee13]

I've been considering getting one of those sonic cleaners. I was just checking them out on Amazon and the smaller ones are really affordable. I remember looking into getting one, probably 10 years ago, and they were much more expensive. Any recommendations on brands or specifications to consider when purchasing?

 

[Woodwackr]

I've been considering getting one of those sonic cleaners. I was just checking them out on Amazon and the smaller ones are really affordable. I remember looking into getting one, probably 10 years ago, and they were much more expensive. Any recommendations on brands or specifications to consider when purchasing?

I got this one 5-6 yrs ago. It is great for smaller stuff like carbs and small hardware from disassembled saws.
I have a larger one that has room for a couple case halves I got for cheap at an estate sale.

https://www.harborfreight.com/25-liter-ultrasonic-cleaner-63256.html

I use Berryman's non spray carb cleaner for carbs, cranks, bearings, etc. Otherwise parts get Dollar Store 'Totally Awesome' cleaner for general parts in the small sonic and a combination of Dawn, tide liquid and water in the big tank for plastics.

 

[StaggerLee13]

Awesome, that's perfect. It's even in stock at my local harbor freight. I might go pick one up tomorrow. Thanks for the info, much appreciated.

 

[Woodwackr]

Awesome, that's perfect. It's even in stock at my local harbor freight. I might go pick one up tomorrow. Thanks for the info, much appreciated.

mine has been overused and beat to death...still going.

 

[EFSM]

These carburetors have an accelerator plunger behind the throttle shaft with an o-ring on it. That o-ring deteriorates from ethanol and allows the high side to pull air around the plunger. This is likely your problem. The 170 carburetors didn't have this, but they were unadjustable unfortunately.

 

[Woodwackr]

This is pretty cool. Shows how to replace that ring.
Thread 'Essential Carburetor Repair Tools'
https://opeforum.com/threads/essential-carburetor-repair-tools.30594/

 

[EFSM]

This is pretty cool. Shows how to replace that ring.
Thread 'Essential Carburetor Repair Tools'
https://opeforum.com/threads/essential-carburetor-repair-tools.30594/

I was too lazy to post that link but I should have mentioned it. Thanks.