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Stihl MS 180C running problems, bogging down, fuel starvation??

Started by rstarkie, June 05, 2013, 09:10:39 PM

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rstarkie

I am a new member, this is my first post.

I have a Stihl MS 180 C saw that has been trouble free until lately.  I bought the saw new about five years ago.  I always use 89 octane gas and Castrol 2 cycle oil.  I cut about three or four cords of firewood a year.  Not sure of the hours on the saw but I just replaced the original sprocket due to wear.

The saw starts fine.  No change in start up over the life of the saw.  In the last several months it has begun to display an intermittent problem that I can only describe as "bogging down" or fuel starvation.  Sometimes it is at the beginning of a session sometimes half way through while others times it is near the end.  It does not seem dependent on the amount of fuel in the tank; although it may be more pronounced when I am reaching up with the saw (engine tipped back).

The bogging occurs at higher throttle positions.  It will idle and pick up off of idle well enough but when a power demand is placed on the engine for cutting it just bogs down.  If I don't close the throttle when it bogs it will just die.  It is doing it more often now than it was, but sometimes it will cut fine for ten minutes or so before once again beginning to bog down.

The air filter is new as is the spark plug.  I removed the muffler to see if there might be some restriction but there was not.

If this saw had carb adjustments I am pretty sure I could solve the problem by simply adjusting the high speed mixture (or at least it seems that way).  When I mentioned the problem to my dealer I saw dollar signs register in his eyes as he explained that perhaps it needed a new carburetor.  Yikes!

Anybody have any ideas of what I might try to solve this aggravating problem?

Thanks,  Randy

shinnlinger

Hi Randy and Welcome,

Do you store the saw with gas in it?  Ethanol gas, which it almost certainly is at 89 octane, is hard on a saws fuel system.  Have you changed the fuel filter?  I would start with that and check the impulse and fuel lines for cracking while in there.  It may also be the diaphragm in the carb is loosing its pop due to the ethanol and a rebuild kit might be in order.  Most kits for that are in the $10 range so I would try the rebuild (if you can find a kit for that carb)before buying a new carb. 

Especially  for that saw.  I wouldn't throw alot of $ at it, but what is a new carb for it anyway?  It sounds like you could bolt a new one on yourself and save some $ that way.

Dave
Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

shinnlinger

Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

thecfarm

rstarkie,welcome to the forum. Fuel filter is an easy fix. You said you looked at the muffler,the screen too? I only use the highest grade I get get for gas, in all my small engines,but that is what I do. Others use what you do and never have a problems.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

deerslayer

My 018C which is nearly identical started doing that as well and it turned out to be the fuel line had a pin hole in it. If you have never changed the fuel line, do that and go from there. I think I paid about $9 at the Stihl dealer for the line. They are available aftermarket but by the time you pay shipping you won't save anything.
Too many chainsaws, not enough wood.
Stihl, Husky, Craftsman, Mac, Homelite, Poulan. Some live here, some just passing through.

joe_indi

The carburetor on this saw has an adjustment only for fine setting the idle speed, that is all.
Considering its 5 years old, some of  possible causes for your saw's problem could be:

A partially blocked pickup body.
A blocked muffler
Engine pan is loose and allowing air to leak in
Seals are ready for replacement.
Carburetor issue would be a remote possibility.
If it does have a carb issue, which mine had, cleaning out the carb with a cleaner (I used soapy water  :D) will get it working again

Joe

rstarkie

Thank you for all the suggestions.  I am going to dive a little deeper into the fuel system and hope I don't get into trouble  :D

The saw gets year round use so yes there is usually gas in it.  I will pay particular attention to the possibility that the ethanol has softened things up when I get in there.

I took the muffler off because I expected to find a screen that might have carboned up but there was no screen.  Very little carbon buildup in the muffler; certainly nothing to cause a restriction.

I will post back with the results.

Randy

rstarkie



So I peeled things down to where I could get the carburetor off.

The filter in the tank did not have any foreign material on it, and the tank was surprisingly clean.  The fuel line was not compromised in any way either.  I carefully removed one side plate and then the other on the carburetor.  I did not see any evidence of foreign material other than what I assume is the atmosphere side of the diaphram.

I did not see any plastic components internal to the carburetor so I am think of using some spray carb cleaner to flush it out.  Is that a bad idea?

So while I had hoped to find something that would point to the source of the problem that did not happen.

Randy

beenthere

rstarkie
Your pics show a brown residue that almost looks like someone dumped brown sugar there.
What is it?
No mention of it in last post that I could detect.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

T Welsh

Randy, I think you found your problem :D :D :D :D :D
Soap and water will do you fine, and carb spray through the carb body,stick it back together and see what happens. I usually get a carb kit when I have problems with carbs, it saves me time and with the ethanol in today's gas it never hurts. Good Luck, Tim

rstarkie

The photo shows fine oil soaked sawdust that was on outer surface of the diaphragm.  I believe that side is open to the atmosphere to allow unrestricted movement of the diaphragm.  Perhaps the residue was preventing the diaphragm from moving?  I cleaned that out of course.  I wish I had a carb kit to put in it as I would rather not have to revisit the area if it runs well after putting it back together.

It is a good time to replace the pull cord so that will get done as well.

Randy

joe_indi

Randy,
Your photo shows the root cause of the problem.
That sawdust between the cover and the diaphragm causes the diaphragm to get pressed down, which in turn causes a higher fuel level in the metering chamber.Or even partial flooding.It is the richness in the fuel that causes the saw to die.
The saw dust moving around will cause  erratic running. Sometimes rich, sometimes normal, depending on where the saw dust is at a given time.
Just clean out that saw dust and your saw should be fine.

Joe

rstarkie

I got it all back together and apparently the sawdust against the diaphragm was the problem.

It starts and runs fine.  It was dark, however, and I am not practiced at using a chainsaw in the dark  ;D.  I did have a nice piece of 10" log that I made two cuts on and no hint of bogging down.  I will run a couple of tanks through it tomorrow just to be sure.

BTW that sawdust was routed through the air filter.  The O ringed circular protrusion in the photo connects to the air box.  Apparently I need to change the filter more often.

Thanks so much for your help.

Randy

joe_indi

Quote from: rstarkie on June 06, 2013, 09:50:21 PM


BTW that sawdust was routed through the air filter.  The O ringed circular protrusion in the photo connects to the air box.
That is the air compensator.It automatically leans out the fuel if the air filter is blocked.But the downside is what happened in your case, sawdust on the metering diaphragm, which causes the causes the fuel supply to become richer.
Joe

rstarkie

The satisfaction of a successful fix for this problem was short lived.  About ten minutes into cutting yesterday the saw started bogging again. 

I can not tolerate having a piece of equipment that is offline and not functioning correctly.  I called my local dealer and found that he could supply a new (Stihl packaged) carburetor for $25.  We did not talk long enough to figure out exactly how much a kit would be for this particular carburetor, but it would have been at least $16, so I opted for a new carburetor.  I also purchased a new fuel line. I had some trouble getting the throttle rod to stay in position during reassembly but finally managed to get everything in place.

I ran two tanks of fuel through the saw and the problem did not resurface.  So I hope it is safe to assume that the carburetor was the solution.

Thanks again for the support and suggestions.

Randy

deerslayer

Don't throw the old carb away. There is likely nothing wrong with it. If the old one was getting filled with crud, the new one will too.

Are you keeping your chain sharp? A dull chain can cause these sorts of problems since they create fine dust instead of chips.
Too many chainsaws, not enough wood.
Stihl, Husky, Craftsman, Mac, Homelite, Poulan. Some live here, some just passing through.

Remeto

I have same problem ms180c starting just fine idles great give it gas and boge and dies have replaced carb fuel line cleaned screen in muffler any other ideas ? Coil maybe?

Submariner

I have a MS 180.  Mine bought the farm a month ago.  the dealer said that I burnt the piston and now it is not worth fixing.  and it won';t be covered under warranty because I over worked it.   even though I used the special Stihl synthetic oil mix.

Has anyone got a suggestion on what I should do now with this saw.

realzed

Make sure whatever your feeding you saw from (jerry can or whatever) isn't full of sediment - all of the crap is coming from somewhere and it could be at the bottom of your fuel source.. Many guys leave their open fuel container(s) sitting close by for quick and easy fill ups when cutting, so they don't have to go far to refuel - and often the dust and finer chips can accumulate in the can if it isn't closed up each time after it is used!  

Air Lad

Quote from: Submariner on December 14, 2018, 01:42:06 PM
I have a MS 180.  Mine bought the farm a month ago.  the dealer said that I burnt the piston and now it is not worth fixing.  and it won';t be covered under warranty because I over worked it.   even though I used the special Stihl synthetic oil mix.

Has anyone got a suggestion on what I should do now with this saw.
Hi I'm new also
A friend gifted me a ms170 he burnt out which his dealer recommended not worth fixing,(this advice was fair enough as the replacement cost of this little,entry level saw was low compared to parts and labour).
Anyway I like a little tinker after work so I stripped it down (first time on a Stihl but youtube is you're friend for this), and found the piston melted,ring stuck and barrel seemed scored. I gave the bore a rub with wet and dry sandpaper and kerosine and it actually cleaned up ok.
A new piston,ring and gudgeon pin ($31.00 AUS), fuel and oil lines,carby strip and clean,careful re assebbly and she's a beauty mate!
I assume the barrel had a build up of piston alloy and wasn't scored at all
You'rs may be the same
Cheers

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