Stihl ms 180 running rich

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pafire

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A friend brought me his Stihl ms 180c with the complaint that it would not rev up. This saw is used as a weekend home owner. After checking the muffler for carbon, and found none. Next removed carburator and checked the metering lever which is level. the diaphram. The saw is still running too rich to rev up to its potental. The fuel line and filter looked ok with no sign of any leaks. Also the piston does not have any scratching. I'm puzzled as to what could be causing the overly rich fuel mixture, that is not allowing this saw to rev up. the muffler is also wet after running the saw. Normally the ms 180 has bog problems and not getting enough fuel. This saw is getting too much.What are the options, as I'am puzzled by this.
 
How does the air filter look?

Everything clear on the throttle linkage letting it hit wide open?
 
Sorry I forgot about the air filter. It looks brand new. The choke and throttle are working as they should. The saw will start and run, however it will not reach full power because it running too rich.
 
Dump out the fuel. Start and run the saw. Run it until it runs totally out of fuel and stops. If it runs up to full speed as it runs out of fuel, then go through the carb, and replace/adjust the needle, [polish the seat too]....
 
i had a 180 do the same thing did a leak down test and it passes so i sprayed carb clean around intake boot after putting carb back on and it died i installed new intake boots ran perfect matter of fact i just sharpen saw for the guy yesterday the carb a very very very cheap on ebay
 

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  • Service Manual 017-018 (MS170 MS180).pdf
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Update to running rich
Dumped the fuel and ran the saw out of gas, it did not speed up whenever it ran out of gas. Went thru the carburetor again and set the metering lever level with the carburetor body. Removed the intake shroud and retightend the carburetor, started saw and sprayed carb cleaner around the intake boot with no change. I did notice the carburetor spraying fuel out of the carburetor intake and the muffler had an oily film on the outside. I’m just out of ideas, maybe its time for another carburetor.
 
trust me when you install a new carb also do the boot there cheap on ebay i have also had that problem and tested it with carb cleaner no change put a new boot on and ran great
 
bought a new hutzler carb, replaced the intake boot, replaced the fuel line and filter still has the same problen in that it will not rev up and it is spitting gas from the carb and the muffler is wet. This is becoming frrustrating, so what am i missing here ???
 
Yeah, the running out of gas test was to determine if the problem was due to a flooding/over rich carb, which if
it was, then it would have sped up and ran great as the saw was running out of fuel. So you need to start looking elsewhere, like the ignition. What does the piston look like on the intake side? Have you tried a fresh batch of fuel?
 
Update: Many thanks to Brad (blsnelling ) it was the spark arrestor screen, it was 95% blocked. I don't know how it ran as well as it did. That could have been the problen from the start, Oh well he now has a better carburator with adjustments. Would a muffler upgrade be worth doing to this saw.
 
The stock carb for that saw is not tunable. Replaced it with a walbro 215 because it has adjustment screws for tuning. Just wish that I had run the saw before the carb change, just wanted to see if there is any difference in power with the carb change. I'm thinking about doing a muffler mod to see if that helps this saw.
 

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