O.T. Stihl chain saw

Robert Zack · May 22, 2022

i have a stihl farm boss ms 290. it's been a reliable tool. used it 4 months ago & did not run the gas tank dry. i use sea foam in my fuel. tried to start it this morning & it would not pull. felt like a hydraulic lock. chain brake was NOT engaged. pulled the plug & the rope pulled normally so i reinstalled the plug, gave it a small shot of ether & it started & faltered & went back back the hydraulic lock mode. any suggestions?

6 SLY PLACE · May 22, 2022

Maybe your pull starter is coming apart inside

Den N Ms · May 22, 2022

Robert Zack , Check for the carburetor flooding over causing hydraulic lock.It could have trash under the needle valve causing gas to leak into the cylinder causing hydraulic lock.The primer pump just pumps gas past leaking needle valve into the cylinder.

This post was edited by Den N Ms on 05/22/2022 at 09:11 pm.

Robert Zack · May 23, 2022

don't think it's the rope since it pulled normally when i removed the spark plug. there's no primer bulb on this saw but the carb could still be flooding. when i initially tried starting it it was in the locked mode. all i'd done was set the trigger in the choked mode. the rope does move a little but it's too tight to get a good pull. thanks for the input. i'll try again tomorrow. i'll definitely run it until the tank is empty in the future especially since they are raising the ethanol content in gasoline.

Btzj02 · May 23, 2022

I have never seen this problem myself but is it possible for clutch to lock up? I have replaced clutches before due to broken springs....

Robert Zack · May 23, 2022

with the spark plug removed it pulls normally so i do not think it's the clutch. i'll take it to the shop today. i have more pressing issues to deal with. i'm doing a neck reset on a 1942 martin guitar that the owner needs back so he can tour with it.

Eman85 · May 23, 2022

That's head scratcher! Carb isn't gravity fed so I really don't see how it's hydraulicly locking the cylinder. I would not spray starting fluid in anything I wanted to keep.

HarryVanderpool · May 23, 2022

(quoted from post at 21:08:22 05/22/22) It could have trash under the needle valve causing gas to leak into the cylinder causing hydraulic lock.

Are we forgetting how a 2 cycle engine works, boys & girls?
Does air / fuel mix flow into the cylinder from the carb like on a 4 stroke?
:roll:

lha · May 23, 2022

On a 2 stroke,the air/fuel/oil mix flows through the carb to the crankcase and through ports in the sides of
the cylinder,to the combustion chamber. There are no valves except in some cases there is a reed valve to
close off the carb from returning gasses.

Robert Zack · May 23, 2022

just had a thought. i'll have to dig out my manual but i think there's a compression release that's tied in to the starting procedure that's engaged with the choke. . if so that might not be functioning.

JMOR · May 23, 2022

(quoted from post at 15:58:18 05/23/22) just had a thought. i'll have to dig out my manual but i think there's a compression release that's tied in to the starting procedure that's engaged with the choke. . if so that might not be functioning.

n my Stihl the compression release is a black toggle right on top of the saw.

Mad Farmer · May 23, 2022

(quoted from post at 14:23:23 05/22/22) i have a stihl farm boss ms 290. it's been a reliable tool. used it 4 months ago & did not run the gas tank dry. i use sea foam in my fuel. tried to start it this morning & it would not pull. felt like a hydraulic lock. chain brake was NOT engaged. pulled the plug & the rope pulled normally so i reinstalled the plug, gave it a small shot of ether & it started & faltered & went back back the hydraulic lock mode. any suggestions?

Try pulling the plug and flipping it upside down, see if fuel runs out plug hole. Bottom end might be full of mix. If fuel does run out, [u:8c8b95f3ea]slowly[/u:8c8b95f3ea] pull it over upside down to purge the fuel.

Keep plug wire away from ground........

lha · May 23, 2022

Chainsaws and weedwhackers have a rudimentary fuel pump diaphram that pumps fuel,as a gravity feed would cut
fuel off if not held vertically. If the motor is full of gas,the reed valve [a one way valve between the
carb and crankcase] would block any gas from escaping. You'd have to remove the carb and reed valve case to
get to the crankcase to empty any gas,but it probably doesn't have any gas in it.

Mad Farmer · May 24, 2022

(quoted from post at 16:30:06 05/23/22) Chainsaws and weedwhackers have a rudimentary fuel pump diaphram that pumps fuel,as a gravity feed would cut
fuel off if not held vertically. If the motor is full of gas,the reed valve [a one way valve between the
carb and crankcase] would block any gas from escaping. You'd have to remove the carb and reed valve case to
get to the crankcase to empty any gas,but it probably doesn't have any gas in it.

Stihl 029/290 are piston port engines no reed valve.

Where the carb pisses too much fuel is the metering valve (like a float bowl needle on an N) that has a bad seat or needle. There is also a set metering height, akin to a float level on a N carb. Same side of carb has a metering diaphragm that can go bad.

I have 029/039 IPL and Stihl Shop manual for newer but about same 290/390, both pdfs.

Not sure how to attach them?

Jim L WA · May 24, 2022

Here's another thought. Could the exhaust anti spark screen be plugged up or something?

Mad Farmer · May 24, 2022

(quoted from post at 09:03:12 05/24/22) Here's another thought. Could the exhaust anti spark screen be plugged up or something?

Always worth a check, along with pulling whole muffler and seeing what the P/C looks like through ex port.

Robert Zack · Jun 1, 2022

UPDATE
had time to check out this saw yesterday & it pulled normally but wouldn't start. i bought fresh gas, drained the tank refilled the saw, & it started. the old gas was only 7 months old & had seafoam in it. i guess i'll only buy 1 gallon at a time when i need to run this saw. and now that they're raising the ethanol content all of us running older machines & small engines will have to be even more vigilant in their care. actually as seldom as i use this saw i should probably sell it & go cordless. my days of working in the timber are over.

Jim L WA · Jun 1, 2022

I know what you mean Robert. I bought a cordless 14 inch Stihl a couple of years ago. I sure like it.

Robert Zack · Jun 1, 2022

like i said i'm not felling trees anymore. doing light cutting around the house, cutting open downed trees to remove beehives, & cutting up free firewood from C.L. is all i use a chain saw for anymore. rural king had a sale 2 years ago & i bought a dewalt string trimmer & leaf blower for $189.00 & love them. i sold my echo trimmer & stihl blower & never looked back. i need a tree removed from my yard. i think i'll try giving the saw in a partial trade for the removal.

O.T. Stihl chain saw

Robert Zack

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6 SLY PLACE

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Den N Ms

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Robert Zack

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Btzj02

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