MS290 stalling when coming off throttle

[jesseoshea]

Hello guys. I have a MS290 that runs great at idle and great at WOT. When coming off the throttle it tries to stall but I can catch it most of the time by babying/feathering the throttle. It’s relatively easy to start.

I have done a few things:

New OEM fuel pickup hose and filter
New OEM spark plug
Fresh fuel and OEM oil
Cleaned and tested the fuel vent line and vent
Basic inspection
Took muffler off and inspected piston and bore. Looks brand new. Saw is 15+ years old but rarely used.
Cleaned air filter
Also attempted to adjust the carb but now sits at factory settings

I cut a massive oak that had fallen yesterday afternoon and it runs pretty good. Completed the job other than a few stalls and being annoying that it tries to stall a lot. Sometimes it will stall when going from idle and into the gas but mainly when coming off of the gas. Throttle response is good and it will idle on the ground without issue. Restarting after a stall is somewhat difficult. I have found that one pull on full choke, then about 3-5 off choke with the throttle at wot it restarts the easiest.

I’m mechanically inclined and have ordered a new oem carb rebuild kit and new oem impulse line and plan to try that next. But thought I would ask on here if anyone has advice based on their experiences. I’m going to try and upload a short video.

For clarity it doesn’t try to stall while WOT or Idle. So in the video it stalling is when I come off the gas and I attempt to feather it to stay running. It will die if I just let off the throttle. Thanks to all that take the time to read this. I know it’s long winded but would like to provide as much info as possible

 

[Kenskip1]

From your information it sounds like the low speed mixture is to lean. Turn the adjusting screw closest to the cylinder turn it out (counter clockwise) a quarter of a turn. See what happens. If this doesn't fix it put the carb kit into it.

 

[Wood Doctor]

I think Kenskip1 is on the right track, but OP may have a plastic delimiter screw that prevents that adjustment. If not, then he may also have to next turn up the idle screw a quarter turn.

 

[ballisticdoughnut]

If the limiters on the carb are still present pull them. Sounds to me like you need to adjust the low speed mixture.

 

[Captain Bruce]

Always replace the entire carb.....the time to kit re-build is no longer validated.

 

[cookies]

I would suggest finding the beg for manuals thread to request the repair manual and with the aid of a tach set the carb to the factory rpms by the book. More than once I have flopped on getting the throttle stop set screw set correctly throwing off the low jet so I fiddled with the low jet, then rebuilt the carb only to find my mistake later...also found a few with bad check valves requiring a new carb.

 

[stihltech]

Vacuum and pressure test before firing the parts cannon. Experience does say a carburetor. Age is more the issue..

 

[magreeable]

Hello guys. I have a MS290 that runs great at idle and great at WOT. When coming off the throttle it tries to stall but I can catch it most of the time by babying/feathering the throttle. It’s relatively easy to start.

I have done a few things:

New OEM fuel pickup hose and filter
New OEM spark plug
Fresh fuel and OEM oil
Cleaned and tested the fuel vent line and vent
Basic inspection
Took muffler off and inspected piston and bore. Looks brand new. Saw is 15+ years old but rarely used.
Cleaned air filter
Also attempted to adjust the carb but now sits at factory settings

I cut a massive oak that had fallen yesterday afternoon and it runs pretty good. Completed the job other than a few stalls and being annoying that it tries to stall a lot. Sometimes it will stall when going from idle and into the gas but mainly when coming off of the gas. Throttle response is good and it will idle on the ground without issue. Restarting after a stall is somewhat difficult. I have found that one pull on full choke, then about 3-5 off choke with the throttle at wot it restarts the easiest.

I’m mechanically inclined and have ordered a new oem carb rebuild kit and new oem impulse line and plan to try that next. But thought I would ask on here if anyone has advice based on their experiences. I’m going to try and upload a short video.

For clarity it doesn’t try to stall while WOT or Idle. So in the video it stalling is when I come off the gas and I attempt to feather it to stay running. It will die if I just let off the throttle. Thanks to all that take the time to read this. I know it’s long winded but would like to provide as much info as possible

I purchased a new Stihl 194t last week that was doing the same thing. The store had put premix in it to ensure it would start. I dumped that stuff, put in mixed gas with a tiny bit of seafoam. The saw runs good now. FYI

 

[jesseoshea]

Hey guys, thank you for the great information. I’ll start with the low speed adjustment. I also purchased a tach to set the high speed jet too. I’ll remove the limiter caps if needed. I appreciate everyone’s input and will update hopefully this afternoon. If not, it will be the beginning of next week.

 

[TRTermite]

Hey guys, thank you for the great information. I’ll start with the low speed adjustment. I also purchased a tach to set the high speed jet too. I’ll remove the limiter caps if needed. I appreciate everyone’s input and will update hopefully this afternoon. If not, it will be the beginning of next week.

With the replies you have received you are taking the course of action I would. The Tach is nice and I should really start using mine more but the "Tuning by Ear" Is my Lazy Way.
Welcome To AS

 

[trains]

One thing to check when that happens, it could be that the high speed side is too rich, and when it comes down off wot, it basically floods the saw.
The video wont work for me, so cant hear it, but when you tune with the tach, check to see its not running too rich on the high side.
if you go leaner and then the saw rpm just drops low after wot, then slowly comes back up, its still to rich on the h, go leaner again till it dosent drop as much, and your pretty close.
Again, this can be used as a diagnosis, but if your ending up really lean on the H needle, you have other issues you need to sort.
You mentioned your at 1 turn out on each, and that should not be that rich on a h needle, there is something else going on that is your problem.

 

[Pioneer]

What trains said. I find the same thing, if a saw dies right after coming off of full throttle it's probably too rich on the high side. You want it to come back down off of full throttle and not pick up speed or lose speed after it sits for a while at idle.

 

[jesseoshea]

Hey guys, it’s been awhile but I have an update! It took nearly a half turn out on the low speed jet to solve the problem. I also needed to richen up the high side to bring the WOT rpm down after checking with a tachometer. Guess my ear needs an adjustment. Saw runs great. Can’t believe it was such a simple fix. I did purchase a new oem carb, but going to throw it in the box if there are future issues!

Thanks again! And sorry for the delay!

 

[Wood Doctor]

You were running too lean. I've rebuilt quite a few top ends on Farm Boss saws that looked like they were running straight gas. Running too lean does the same thing eventually. Air leaks from the intake boot will cause it also:

 

[jesseoshea]

Thanks for the tip Wood Doctor, I’ll be checking my intake boot in the near future. Fortunately the piston looked good from what I could see through the exhaust port. Hopefully as is well internally. Happy to have it running again.

 

[user 122190]

If the limiters on the carb are still present pull them. Sounds to me like you need to adjust the low speed mixture.

My 10yo 290 was having problems. Carb rebuild kit and pull those limiters and it ran better then new. At first, I didn't pull the limiters or completely remove and clean the high/low screws. Second attempts in doing the screws made all the difference.

 

[Mike Kunte]

If everything else is in good condition (high-speed set correctly; vacuum test passed etc.) this sounds like your bottom-end it too rich. If it were lean, the saw would run high coming off full throttle, and may even "wah-wah" as it hunts for fuel.... Lean out the bottom end a bit and it should settle down to a nice idle...
To confirm whether it's running rich, it should "bog" slightly when accelerating, and you may have to blip the throttle a few times for a clean pick up. Once you've made the adjustments, it should pick up more quickly too!
My 2c

 

[Vintage Engine Repairs]

I’ve just watched your video, you’re lean on your H screw. It’s not stalling when coming off WOT. It’s actually stalling during WOT due to a lack of fuel or too much air. You mentioned that you richened the L to get a better result. There wasn’t anything wrong with the L really. Maybe a tweak richer would have helped, but it accelerated and decelerated just fine, there was no bog off idle and no stepping down from wide open throttle. The H is your issue, but when you richen the L you give the saw more fuel at WOT too, but it’s not the correct way to do it as you end up giving yourself too much fuel at idle too.

If it was me, I’d have tweaked the L a touch richer and opened the H a fair bit until it 4 strokes clearly and cleaned up under good load. That’s the correct way to have tuned the saw.

 

[Captain Bruce]

Always replace the entire carb.....the time to kit re-build is no longer validated.

Just finished an 1127-series. MS310. The impulse hose had a small split in the bend. Replaced it, put the saw back together, and without an carb fiddlin', it revs, and backs out of, the full throttle curve. Also noticed today, it starts on 2 pulls. 1. FULL choke and it burps with the rope 1/2 extended. 2. 1/2 choke/fast idle...fires and rev's as per tach setting. 3. Blip the throttle and it idles like a drowsing Puppy

 

[TRTermite]

Thanks for the tip Wood Doctor, I’ll be checking my intake boot in the near future. Fortunately the piston looked good from what I could see through the exhaust port. Hopefully as is well internally. Happy to have it running again.

Wood Doctors post #14 showed the "INTAKE" side where the "LEAN" took out the Piston.
Commenting for future members trying to find answers.