I’ve had a ms250 for many years, and it’s been a good saw. The last couple of years it’s been harder to start, runs ok but doesn’t idle very well. I have installed a carb kit, that seemed to help for a short while, but ultimately back to the same symptoms. Air filter is clean, spark plug has been replaced so its not those things. I am debating on just buying a new carburetor and installing. Would this be my best route? I would rather not tinker with it if I don’t have to, just want it to be back to old reliable condition.
Stihl MS250 tune up
- Thread starter Slimdusty
- Start date
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Whitenuckler
Feeling the Heat
Did you clean the carb and blow out all the passages? You could get a new carb and try that. At least with Stihl you can get the parts. Because you made the problem go away by working on the carb, it makes sense that it is the carb again. Maybe take it apart again and clean it and get a bottle of compressed air if you didn't the first time.
Check the air filter seal, and rinse out the gas tank. You could be getting dirt into the carb.
Make sure you have good gas. Water will settle to the bottom of your storage container. Maybe buy a bottle of the premix so you know for sure you have good gas.
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I have an old Stihl 009L - no 'official' parts available anymore but it runs fine now. I did have carb problems for a while - I replaced the inlet filter which is inside the gas tank because it got plugged and also replaced the carb with something from Amazon/China and it works like new (well almost) again. I like to replaced the carbs rather than try and replace parts with a kit. I find some things can't be accessed easily and a new carb fixed that problem.
Whitenuckler
Feeling the Heat
Don't blow out passages in a carb with compressed air
There are check valves that can be damaged with compressed air. Use a can of carb cleaner to clean the passages if you don't have access to an ultra sonic cleaner.
I put my carbs in a jar of Seafoam in the ultra sonic cleaner.
My thought is that there are many parts, orifices, gaskets, seats, etc. inside the carb that I may have missed, or are damaged, which is why I am leaning towards a new carburetor altogether. I can buy one for less than $40, IF its decent quality that is so worth it to me versus spending more time and aggravation with this old one.
I have replaced the fuel filter in the tank, and also the fuel lines.
I have replaced the fuel filter in the tank, and also the fuel lines.
Whitenuckler
Feeling the Heat
I bought a new carb for my lawnmower from Amazon. Honda GVC160 Engine. I had used it for mulching last year, and I put it away dirty.
It was getting hard to start, but still running. It has an auto choke, which I'm not sure I like. Anyway, the machine was dusty and caked on all around the airbox area ect. I got my shopvac out and made up a small nozzle for it. I basically vacuumed it while rubbing the dirt. I then unscrewed the airbox/carb and left the linkages on. I vacuumed more. I then unscrewed the bowl cover and took the needle out. I did some more careful vacuuming again and sucked where the needle seats and the main jet. Put it all back together and started right up. The kit I bought is a manual choke I think, but I just have it as spare now. I can't believe these Chinese kits, carb, air filter, spark plug and some gaskets all for $22. I was in the same situation with my Ariens Snowblower, but managed to get the needle working again, so that Chinese carb is spare too. They are so cheap why not try?
Thanks for the video, honestly the saw that she took apart looked to be in better shape cosmetically, than mine. I”ll still likely see if a new carburetor makes an improvement.
Whitenuckler
Feeling the Heat
Don't blow out passages in a carb with compressed air
There are check valves that can be damaged with compressed air. Use a can of carb cleaner to clean the passages if you don't have access to an ultra sonic cleaner.
I put my carbs in a jar of Seafoam in the ultra sonic cleaner.
Thanks for pointing out that you should not blow high pressure air into your carb. I was wondering where these carb parts you refer to were, and if the carb kit contained these parts. I found a video of a carb and how it works. As far as I can see, the one way valves are part of the pump diaphragm and would be removed if you were re-building the carb.
The operation of the crankcase vacuum/pressure pulse is important, and if you have leaky crank seals the carb will not work properly.
This may explain why I could never get my neighbors old chainsaw going. I believe they can test the crank seals somehow.
When working on a saw that is unknown to me that first thing i do is look at the piston.
Then set up for a vacuum and pressure test. That test is for seals ect. Sometimes a gasket leak will be the issue.
Then set up for a vacuum and pressure test. That test is for seals ect. Sometimes a gasket leak will be the issue.
