[carb...unresolveable fast-idle] Turned Idle so far out the screw fell out and chain still whips at idle :/

[eye.heart.trees]

My groundsaw doesn't see a ton of use (it's a 42cc, my 355t is 36cc so I typically just grab that on-ground since I like its feel better) and it was having 'fast idle' issues when I last used it (~3wks ago) but when I went to 'tune&restore' it yesterday I found I could not resolve the fast-idle at all, even after turning out the Idle screw and having to put it back in*, with it back in (just barely) it was still fast chainspeed, I'd turn-down (CW) the Low jet until it'd choke out, I did this back&forth (was throttling / this isn't just 'fast-idle at startup')

If Idle is pulled-out (CCW) as far as the carb allows, and the L jet is choked off as much as the powerhead allows w/o dying at idle (low-enough that it will die if you touch that trigger), my chain is still whipping around.....WTF?!?


No idea what to do would appreciate any input, FWIW I do have a backup/parts saw for this unit but I cannot even fathom what it could be if not idle/L settings... Thanks in advance for any&all input

(saw is the venerable "Poulan Pro pp4218a", the backup/parts unit is Craftsman branding....this poulan is my 1st-ever chainsaw and it's held its own, it's still more powerful than my highly tuned 36cc echo! Have to wonder how much of that is "saws are better broken-in" and how much validity there is to that sentiment)


*is there supposed to be a spring on the Idle screw? When shaking my upside-down saw to retrieve the fallen Idle screw, I also had a lil black spring fall out, this spring's absence hasn't had noticeable effect on the saw..

 

[Vintage Engine Repairs]

Grease the clutch roller bearing or replace clutch springs

 

[Bob Hedgecutter]

Put all the carb screws back to factory settings and then pull the bar cover off and have a long hard look at your clutch.

 

[sbhooper]

Air leak?

 

[Old2stroke]

Have to be more specific. Are you saying that you can't get the engine speed to slow down and that's why the chain is moving, or even with the engine speed close to stalling the chain is still moving?

 

[J D]

If it truly is idling high all of a sudden look for something mechanical preventing the throttle from returning all the way to the adjustment screw (linkage catching/ bent, return spring broken or caked in crud etc)
If there is nothing holding the throttle up the saw has probably developed an air leak. Given it's lack of use I would suspect perished lines or seals

 

[mountainlake]

When its idling spray some WD40 or similar at the seals, carb boot, base gasket or anywhere it might suck air, If it slows down you found the leak. Steve

 

[bryannewton]

Had i ms250 that went almost full throttle when it would start had carb replaced and I believe they said flywheel seal

 

[hotshot]

Ahoy matey, pressure test that saw as it sounds like it’s got a “pirate air” leak!

 

[Teretonga]

Collapsed clutch drum needle bearing.

 

[Bubster]

A saw that sits a lot will get gunk between the clutch shoes and sprocket drum.Clean that out first.If no help,replace clutch springs.They are actually pretty easy to replace (and cheap)

 

[HumBurner]

Grease the clutch roller bearing or replace clutch springs

Simplest first.

Clutch springs going bad will allow the chain to race,despite all other factors.

 

[FunkyYota]

I had a throttle plate get a little bent once. Kinda acted this way.

 

[dieseldod]

seals are leaking

 

[lone wolf]

Sounds like all the replies have it covered!

 

[stihltech]

So what was it? We need answers!!!!