Stihl MS 290 slows during cut...

[PSJWI]

Hello,

My son has a new Farm Boss / MS290 that seems to run fine until it has to actually produce some significant power as it gets deeper into the cut. Then it just slows up - even if you pull it up from the cut, you have to let up on the throttle and then if you pull on the throttle again it will speed right up. It's not that it's being forced into the cut at all - in fact if you let it just barely get into the cut , it slows right down.

It seems to me like it's starving for fuel - but the high speed jet is as far open as is allowed by the factory stops.

He did have regular gas in it (ethanol) - that was about 4 months old. I no longer use regular (with ethanol) myself, but I did use it for many years and never had this type of problem with any of my Husky saws.

Any ideas?

Thanks,

PJ

 

[EatenByLimestone]

How new is it? It sounds like it needs more fuel to me. Plugged filters/screens? Corrosion in carb? Excessive varnish?

I usually try running Seafoam through a carb before I pull it apart.

Matt

 

[Rock Crusher]

I had the same issue with my Stihl MS 391 with the factory "green" chain. I swapped it out with my spare "yellow" chain, presto, it rips through full width oak and hickory now. I believe Stihl calls the yellow chain Rapid Super Cut or RSC , or something to that effect. One more note-I recommend using True Fuel at 50:1 sold at outdoor equipment stores and the box stores. It costs about $6 per quart, but has no ethanol. At least use it to store the saw and other 2 stroke equipment for longer than 2 months. It worked for me!

 

[Jags]

Those saw were set lean from the factory and have very little adjustment because of the limiter tabs. If it is new - take it back to the dealer and hand it to him. If he is worth his salt, he will adjust the saw properly.

 

[Ashful]

Those saw were set lean from the factory and have very little adjustment because of the limiter tabs. If it is new - take it back to the dealer and hand it to him. If he is worth his salt, he will adjust the saw properly.

+1

One more note-I recommend using True Fuel at 50:1 sold at outdoor equipment stores and the box stores. It costs about $6 per quart, but has no ethanol. At least use it to store the saw and other 2 stroke equipment for longer than 2 months. It worked for me!

Certainly can't hurt... but not even my Stihl dealer recommends this stuff, due to cost. Maybe the occasional cutter can afford it, but it gets expensive quick, if you're using your saws regularly. My dealer recommends and sells the stuff only to those wishing to store their saws for infrequent use, their recommended procedure being to dump the ethanol gas out of the saw and run a little of this thru it, before putting her on the shelf for storage. It will keep 2 years without additional stabilizer.

If you're running your saw daily, as bad as it is supposed to be, most just run regular ethanol pump gas (91+ octane) without any trouble at all.

 

[BKInsert]

Very good suggestions here so nothing much really to add... You said it, most likely starving fuel issue due to bad tune, dirty carb or air leak in fuel line, could also be a partial tank clogged air vent.
I am facing same issues with some of my saws... MS460 has same issue as you right now, I rebuilt the carb (easy to do) but did not remove and cleaned the H/L screw jets, big mistake... I need to do it now. The Dolmar PS5100 had same issue after I rebuilt the carb, when I finally removed the H jet screw there was a small piece of varnish at the needle end... now it has plenty of power...
I think the main issue, like someone mentioned above, is that the saws are not used often enough, if they are used at least once a week then the fuel issue would not exists. I may go the suggested rout about storing the saw with the expensive fuel.

 

[AroostookDave]

After you check your air filter, look at the fuel filter in the gas tank. If it needs replacing, or if the gas line from it is kinked, you will get lack of power when cutting. Long slender needle nose pliers can be handy here.

 

[Bigg_Redd]

If I were a betting man I'd bet the saw runs fine and the problem is a dull or otherwise improperly filed chain

 

[Maple man]

My new ms 290 was a little sluggish for the first 3 tanks of fuel but on the next tank the saw woke up and ate through logs like nothing. I believe their is a break in period for new saws. All I know is my saw ran a lot better after 3 tanks of high octane fuel from the gas station