Stihl ms250 bogging at full throttle

[oakchop]

Good morning all, I have read the entire thread. I smell a troll. Things that jumped out in the OP's posts. Only 10 hours total run time on the saw so he hasn't cut much wood. Rust on top of the piston? Aluminum does not rust!
Just too exact on everything. Everything is perfect. Checked everything that you could possibly check but failed to remove the impulse line and inspect as recommended. They can get hard over time, crack, not seal properly. Found screen clogged in carburetor which in my humble opinion is caused by fuel containing ETHANOL. Anyway, as I said, I suspect a troll. If I am correct, he sure kept everyone busy. LOL
JMHO OT

my chainsaw did have less than 10 hours. It was a display model or "open box" sale (even though Sthils aren't in boxes). It sat for some time after the sales ad said it has been ran a couple times.
I'm not going to sit here and give every single detail to satisfy your needs.
My saw had issues, the exact ones I explained. I seemed to have fixed it with help from folks here.
Have no idea what you mean by smelling a troll.
Im reporting facts. I don't know if the piston is aluminum, I just saw rust on the head. rust can develop anywhere and if it wasn't rust I don't know what it was. It wasn't there after running the saw. I could see orange rust on one side of the head looking through the sparkplug hole.
I never had ethanol gas in my 250 either.
If you read the whole post I think I covered all this in less detail of course.

 

[oakchop]

FWIW, I had a MS362C a few weeks ago that was bogging down and the owner had put some kind of fuel filter in it that the fibers that the filter was made of had clogged up the screen .

Good to know. I need to check my filter closely here in a bit just to make sure.

 

[oakchop]

Store empty. if it ain't in there it can't go.bad.

that's what I've always heard. I just wonder if this can cause issues in super high humid regions. so far I've been storing dry.

 

[oakchop]

Good morning all, I have read the entire thread. I smell a troll. Things that jumped out in the OP's posts. Only 10 hours total run time on the saw so he hasn't cut much wood. Rust on top of the piston? Aluminum does not rust!
Just too exact on everything. Everything is perfect. Checked everything that you could possibly check but failed to remove the impulse line and inspect as recommended. They can get hard over time, crack, not seal properly. Found screen clogged in carburetor which in my humble opinion is caused by fuel containing ETHANOL. Anyway, as I said, I suspect a troll. If I am correct, he sure kept everyone busy. LOL
JMHO OT

Same here in this neck of the woods. (about downtime for a chainsaw)
That is just one of several reasons why I also keep a good running back up saw and also repair my own saws and also I keep a good running light weight saw for trimming small stuff, but it's also strong enough to use on 20 inch firewood logs if needed.

Caution: Start learning how to repair your own chainsaws and if you like to tinker and have patience, you will accumulate many. It gets into your blood.

What happened to the OP? (and his 250)

I'm looking to get a MS261 now. I think I can handle this 250 but I just don't like the lack of power and hot flooding. Which is another thing I'm trying to circumvent.
Does anyone know how to solve this hot flooding phenomenon that occurs after use?
I'm not sure what happened to the Original poster SaltyTimber. They never really chimed in after their post.
Seems I had the same issue and solved it. I didn't mean to take over the post but I had narrowed it down to either the impulse hose and the carburetor. it ended up being carb.

 

[Okie]

Speaking of Stihl impulse hose problems.
I seen a complete Stihl 034 really dirty looking with a good bar and like new chain next to a trash bin and asked the guy if it was being trashed and if so I could use it for parts. he said Yea take it it has low compression and I bought myself a new saw.. The guy was a really good auto mechanic.
I brought the saw home and took couple days outside the shop to get the oil/dirt and grease removed so I could check the saw. Looked like someone has pured 90w differential oil on the saw and then dirt. I would get nasty and greasy just being around the saw. I gave it a prime of mixed gas and it started and ran for little nd would keep doing the same with a prime. Peeked in behind the carb and the impulse hose was off or just barely hanging on the carb.
After I seen it running good I went ahead and checked compression as A ok and took a peek at the piston after removing the muffler. Really a good saw for the firewood wood lot.
A diamond in the rough.

 

[oakchop]

Speaking of Stihl impulse hose problems.
I seen a complete Stihl 034 really dirty looking with a good bar and like new chain next to a trash bin and asked the guy if it was being trashed and if so I could use it for parts. he said Yea take it it has low compression and I bought myself a new saw.. The guy was a really good auto mechanic.
I brought the saw home and took couple days outside the shop to get the oil/dirt and grease removed so I could check the saw. Looked like someone has pured 90w differential oil on the saw and then dirt. I would get nasty and greasy just being around the saw. I gave it a prime of mixed gas and it started and ran for little nd would keep doing the same with a prime. Peeked in behind the carb and the impulse hose was off or just barely hanging on the carb.
After I seen it running good I went ahead and checked compression as A ok and took a peek at the piston after removing the muffler. Really a good saw for the firewood wood lot.
A diamond in the rough.

Amen. This is exactly why I'm here. Learn from others issues that can be solved with self inspection.

 

[cookies]

if you think its a type of fuel bug order or aquire some algae killer diesel treatment and mix it with 2 gallons of mixed gas then fill the tank then let it sit a few days or a week then shake and dump it. buy a couple fuel filters from stihl, preferably the orange version and run it using the treated fuel. Change the filter and clean the carb after running the 2 gallons through it. Fuel bug only lives where moisture is present, it will remain dormant for years until moisture appears again and then multiplies all over again. Glad you found your culprit.

 

[oakchop]

if you think its a type of fuel bug order or aquire some algae killer diesel treatment and mix it with 2 gallons of mixed gas then fill the tank then let it sit a few days or a week then shake and dump it. buy a couple fuel filters from stihl, preferably the orange version and run it using the treated fuel. Change the filter and clean the carb after running the 2 gallons through it. Fuel bug only lives where moisture is present, it will remain dormant for years until moisture appears again and then multiplies all over again. Glad you found your culprit.

wow thats a eye opener. yes as of now it's either 1. mold/mildew/or similar
2. oxidation/filter breaking apart/something white paste-like clogging up the screen and lining the gas tank
I know this doesn't narrow it exactly down but I did FIND it, not so much WHAT it is, yet.
Im looking at bio tank treatments now.
keep in mind my MS250 came from Oklahoma and shipped to Springtown Texas. If you even grasped the insane humidity here you'd know why oak trees grow and die tragically fast here due to disease. and oak trees should live hundreds, some rumored in the thousands of years! Humidity is so bad here that the first time you use a fresh towel to dry off after a shower, your towel develops mildew. we use vinegar and baking soda to wash clothes too and it barely works.
By the way, our Honda lawn mower needs constant maintenance due to moisture effecting the engine and gas tank. our new echo blower is new from HD and it's already experiencing moisture and rust on metal parts.
more often than not our humidity is in the 90s and frequently reaches 100% which produces haze rather than rain. if you've ever lived near an ocean like I used to in Oceanside CA you'll see people's classic cars rims rust out even brand new chrome. destroys metal due to extreme humid salt oxidation. I'm not exactly by the ocean now but I get all the shore weather in central Texas.

 

[cookies]

Im in florida, 7 miles from the gulf of mexico...im constantly dealing with other peoples fuel damaged stuff. in my experience when I find white chalky crap its been from metal oxidation typically from fuel with ethanol that steals ions from aluminum/magnesium/magnesium-aluminum blended. Saw carbs are aluminum and are designed to bleed the fuel back into the fuel tank after shutdown passing the crap back into the inside of the filter body. On metal tank saws it can be the powder coating or exposed metal under it. Start at square 1, your fuel and storage tank...even plastic tanks will give off powder after enough exposure to sunlight. When in doubt dump it out or replace the tank too.

 

[oakchop]

Im in florida, 7 miles from the gulf of mexico...im constantly dealing with other peoples fuel damaged stuff. in my experience when I find white chalky crap its been from metal oxidation typically from fuel with ethanol that steals ions from aluminum/magnesium/magnesium-aluminum blended. Saw carbs are aluminum and are designed to bleed the fuel back into the fuel tank after shutdown passing the crap back into the inside of the filter body. On metal tank saws it can be the powder coating or exposed metal under it. Start at square 1, your fuel and storage tank...even plastic tanks will give off powder after enough exposure to sunlight. When in doubt dump it out or replace the tank too.

you know, Ive had a feeling this whole time that this saw may have had typical gas thrown in it for demonstration purposes. I can't prove this but I've had others tell me the same thing.
now since I've had it (and it was in pristine brand new condition, saw chain and bar) I never put anything but non ethanol in it but if that's what causes this white substance then possibly someone at Stihl in Oklahoma did it, but I just can't see that happening. I do know their sales ad said the saw was ran 2 times. so it did have gas in it. the tank, the carb pump screen all have this white chalk like paste which many are saying it's related to ethanol gas.
Whatever it is I'm going to try to find out locally.
if the problem persists it might be mold. it it corrects after my cleaning I'll know it was something possibly ethanol gas related.
my only suspicion plays on the fact many people out there, even arborist fellas brag and boast about using ethanol gas as long as it's below 10%, meanwhile the other 80 to 90% of pros say NEVER use it under any circumstance.

 

[cookies]

you know, Ive had a feeling this whole time that this saw may have had typical gas thrown in it for demonstration purposes. I can't prove this but I've had others tell me the same thing.
now since I've had it (and it was in pristine brand new condition, saw chain and bar) I never put anything but non ethanol in it but if that's what causes this white substance then possibly someone at Stihl in Oklahoma did it, but I just can't see that happening. I do know their sales ad said the saw was ran 2 times. so it did have gas in it. the tank, the carb pump screen all have this white chalk like paste which many are saying it's related to ethanol gas.
Whatever it is I'm going to try to find out locally.
if the problem persists it might be mold. it it corrects after my cleaning I'll know it was something possibly ethanol gas related.
my only suspicion plays on the fact many people out there, even arborist fellas brag and boast about using ethanol gas as long as it's below 10%, meanwhile the other 80 to 90% of pros say NEVER use it under any circumstance.

arborists run the saws every day never allowing the saws or fuel to sit and thats why they have so few problems from ethanol, but once they let them sit a couple weeks they get hit with the gremlins.

 

[Sidecarflip]

My saws sit for months in the shop and I NEVER have fuel problems because I only run canned Red Armor fuel. and maybe 40-1 Tru-Fuel to break in a new saw. Like everything in life today, you get what you pay for...,

 

[SteveSr]

FWIW, I had a MS362C a few weeks ago that was bogging down and the owner had put some kind of fuel filter in it that the fibers that the filter was made of had clogged up the screen .

Can anyone say AFTERMARKET fuel filter?

 

[SteveSr]

I'm looking to get a MS261 now. I think I can handle this 250 but I just don't like the lack of power...

Best thing to do with these is to convert them to 16" 3/8" LP (Stihl Pico) bar and chain like its smaller siblings. Works MUCH MORE better! Unfortunately, this entails a bar, chain, and sprocket swap. Now would be a good time to put on a rim sprocket conversion as well.

...and hot flooding. Which is another thing I'm trying to circumvent.
Does anyone know how to solve this hot flooding phenomenon that occurs after use?

I have never seen these flood hot. If it is actually flooding you have a carb needle and seat leak.

However, this saw (and any other saw) will vapor lock, especially if you are using winter fuel in warmer temperatures.

The other trick which will likely help is to let the saw idle for 30-60 seconds before shutting it down to give it a chance to cool off.

 

[ballisticdoughnut]

The MS 250 has the WORST air filter set up ever and will quickly bypass the filter as the little thin plastic box deforms from the restriction

I agree. Swapped mine for the early two piece clamshell style filter. Problem solved.