I'm sorry if this is a little off topic.

I have a Stihl FS131 string trimmer. Its maybe 2-3 years old. It gets used frequently during the growing season and chills out during the winter. I only run non-ethanol in the machine. During the winter I crank it up every 2 weeks and let it run for a bit.

Currently, it cranks up easily and runs great. The issue involves idling. If I'm trimming and need to set the trimmer down for a minute, the machine will shut off within a minute or so. I changed the air filter and I am still experiencing this problem.

How can I correct this?

Did you check the fuel filter within the fuel tank?

Change the spark plug and then up the idle a little bit on the adjustment screw of the carb. Or the valves may need adjusting as it is a 4 smoke engine even though it runs on mix

Exhaust screen could be plugged as well. LLL

Fuel filter or the little nipple may be cracked.

I've used them my whole childhood. Best bet is go take them to a Stihl dealer and have it repaired. Ask them what it was.

Have you tried using fresh gas? Most places recommend you dump your gas out every 30 days and replace it with new. Your cab may be gummed up as the result of old gas and a tune up may also be in order.

Start with the easy things first.
Dump the gas for new. (Make sure your gas can does't have water in it first.)
Change the spark plug. They are cheap and even clean looking ones can be bad.
Remove the spark arrestor from the muffler.

Do all the above . Mine turned out to be the spark arrestor screen .

Two things.

1) There is nothing you can come up with that is off topic for this site.

2) Your trimmer sounds like it runs better than any gas trimmer I've ever owned. I was happy when they started.

That screen is more trouble than it's worth to me.

There's an idle adjustment screw you can play with too.

2 stroke wont idle but runs like a banshe at hi often = air leak and running lean

My dad said it could be the regulator

Don't mess with the screws to much my dad said you could really foul it up and it will never run right.


Definitely bring it to a dealer. It's not worth screwing up.

On ebay you can get a kit that has: filters, plug, and a new carburetor pretty cheap. Get the kit, change it all, and whatever it was should be fixed.

Remove spark arrestor from muffler and throw it away.

Mine doesn't idle at all.

It's a Milwaukee cordless

Throw away the spark arrestor and floor it.