Stihl - weedeater - engine runs erratic

[GaryDG]

I have Stihl weedeater. I push the primer button 3 times, put the choke on and pull - it starts right up. I take the choke off and the unit runs as it should. After approximately 5 minutes of normal use the engine starts to oscillate (normal rpm to low rpm to normal rpm) then run as if it wants to die. By constantly depressing and releasing the accelerator lever I can keep the thing running for a while but after about 8 minutes of running erratic it dies.

The only thing I can think of that is causing this is some type of heat related issue - that is once the engine heats up the issue occurs.

 

[kevin37b]

I hope you mixed the fuel correctly .

 

[tow653]

There is a similar post about Stihl's having problems with the exhaust/spark arrestor being plugged,check that out.
http://www.tractorbynet.com/forums/rural-living/357792-constipated-weed-trimmer.html#top

 

[CobyRupert]

Hopefully it is exhaust being plugged, but maybe also do a poor man's compression test: How hard does it pull when cold as compared to how hard does it pull when hot? Or with a gauge if you have one.
If your piston rings are shot, and/or cylinder walls are scored, she might not be making compression, this might be a harder fix.

 

[rswyan]

First time you've used it this season ?

Issue just show up ?

Did you drain it and run it dry at the end of last season ?

 

[dieselcrawler]

I had a similar issue... $26 later a new carb fixed the issue. Common problem according to my local stihl dealer. Same issue with a concrete saw at work, new carb, runs like new.

 

[Will_C]

I had the same problem last year with my FS250. The carb cost more than $26, but it has been running fine ever since-started it up yesterday and used for the first time this year-4 pulls and I was in business.
The dealership I use told me they don't even mess with the carbs on consumer grade Stihls-they just replace them for around the $26 mentioned earlier.

Will

 

[dieselcrawler]

*grin* The carb on the concrete saw at work (TS420) cost 3x what my lil string trimmer carb did! But same awesome results.

 

[5030]

Blame all the above issues on crap E-gas. You have to stabilize it, drain it or buy ma new carb every year. Thanks Obama....

 

[dieselcrawler]

The gas issue is why I don't put 'regular' in my cans. Be it saws, weedeaters, lawn mowers, or generator, it will likely sit a while in the can or in the tank... so I buy the better stuff. And the 4wheelers run better on high test too.

 

[5030]

The gas issue is why I don't put 'regular' in my cans. Be it saws, weedeaters, lawn mowers, or generator, it will likely sit a while in the can or in the tank... so I buy the better stuff. And the 4wheelers run better on high test too.

I do too.... and I add marine Stabil as well. Stuff is junk

 

[dougbthom]

Over a number of years of using Stihl products ( blowers , weed, weedeaters and chain saws) I have used a product called Sea Foam in the "premium fuel only" twice a year, at the start of the season and once just before the end of the season, and eliminated any and all sluggish engine problems. You will see a difference within 5 minutes on any engine you use this on. I add about an ounce or less per engine each time and the engines run beautifully. The other thing I do is use only synthetic oil whether it be 2 cycle or 4 cycle engines and find that they run much better. In my case I use Amsoil synthetics exclusively. The 4 cycle oil I use is Amsoil 4 cycle 10W-30 SAE 30 and 2 cycle oil Amsoil Saber Professional mixed into the fuel. It's a 100 to 1 mix ratio in 2 cycle engines but I mix it about 75 to 1 ratio with great results. Hope this helps!