my saw wont start and firewood has arrived

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vasten

Member
Nov 11, 2007
205
Upstate NY
My log load arrived the other day and I got all excited. Got my gas all mixed up, filled up my bar oil. and started the saw. I made about 20 cuts when she stalled out, and that was the end of it hasn't started again.

The saw is a 041 AV, when it stalled out I checked the kill switch to see if I bumped it and almost burned my finger it was so hot. Obviously let the saw cool off (and me too ) for a few days. When I went back out I noticed one of the vaccuum lines from the carb to the front of the saw was off. I reattched that and nothing. Took it to my local Stihl dealer and we replaced that line and a new air filter, and spark plug. I am getting spark, checked by first grounding plug to side of saw and pulling over, then with it in the saw and a plug tester. Compression test shows it pulling 90 lbs of compresson. When investigating further noticed that muffler had litterally come off, I put that back on and still nothing.

I have put gas in the carb, directly into the cylinder through plug hole and even tried either in both of these ways and still wont pop. It has nothing going on.

The saw is sitting on my buddy's work bench now, waiting, looks like today we are going to try to get to the coil. our thoughts are that the coil is not putting out a strong enough spark consistantly. thinking it could have gotten fried when it got hot. The other option is that the engine is just worn out, and rings and etc are shot, but if so, then not thinking it would pull 90 lbs of compression.

When I was cutting with it, it smoked like a mother, I just figured it was the gas/oil mix and it would clear, and the casing temp would make sense from the muffler being off, inside the machine and dangling there. If it couldn't vent out through the muffler it was venting inside the casing in turn heating that up.

Before I tear the saw up anymore any suggestions would be appreciated, thank you
 
Fuel, spark and compression it should run. What compression range did the stihl dealer say the saw should have? For example a good running 361 will usually have around 150 psi. Also with the muffler off you should be able to see the piston for bad wear. The exhaust side is usually the side that gets cooked if the engine burns up. If it looks questionable post a picture of it. You may want to post this on www.arboristsite.com they're a good group of guys.
 
Good suggestion. While looking, check to see if the high heat melted the wiring insulation going to the switch. It could be shorting to the case.
 
I am by no means an expert, but I believe 90 psi compression is very low for a chainsaw. The general rule of thumb I've heard is a minimum of 120 psi measured for a saw to be able to start and have any kind of operating power.
 
wayneg said:
I am by no means an expert, but I believe 90 psi compression is very low for a chainsaw. The general rule of thumb I've heard is a minimum of 120 psi measured for a saw to be able to start and have any kind of operating power.
+1
 
I bet you had a lean mixture from wrong mix or you used a fuel blend with ethonal(sp?) Take off the muffler again and look at the piston. Dont worry your not the first one to cook your old saw. This is very common with the new fuels out there. 90 psi is way low for that saw.

Let us know.
Rob
 
I checked the wiring and it appears to be fine, no marks, knicks, or melted sections. It looks to me that it is all coming back to the compression. One thing I am wondering is if the compression read low because there was no back pressure from muffler. I didn't realize the muffler was off until later on.

Piston was shiney and decent looking from what little I could see through the exhaust port. Nut that is only one small section of the entire piston and it doesn't take much to kill your compression.
 
In your post on Arborists site you asked the same question about your o41. The people at that site are first rate. Do you not trust their judgment? I am also a member their. I also have an O41. This is what made me take notice of this post. BTW, you will never get it going very well with only 90PSI


Just a note, I lived in Oneida county for 20 years. Near the city of Rome. Griffiss AFB to be exact
 
actually I started the post here, and was refered to the arborist site from here. It appears that the consensus is that these guys know their stuff.

But it was on this site that someone mentioned ethanol, which clicked with me that yes my gas station does add it at 10% to their gas now. which threw the mix ratio way off.
 
vasten, Always check compression with the throttle wide open. It should run with 90psi. What you may need to do is a leakdown test. You may have blown out a crank seal. 90 is low but it is enough to run.
 
fyrwoodguy said:
all most all the customers i quiz about "stalled in the cut" end with seized up piston :-/
That was the end result. I got the saw started today and it ran great. Cut for close to 2 hrs, then stalled out and DONE. That pistion locked tight.

So look for my new post on opinons of what saw to get to replace it.
 
vasten said:
actually I started the post here, and was refered to the arborist site from here. It appears that the consensus is that these guys know their stuff.

But it was on this site that someone mentioned ethanol, which clicked with me that yes my gas station does add it at 10% to their gas now. which threw the mix ratio way off.

That IS what they tell each other.
 
Bigg_Redd said:
vasten said:
actually I started the post here, and was refered to the arborist site from here. It appears that the consensus is that these guys know their stuff.

But it was on this site that someone mentioned ethanol, which clicked with me that yes my gas station does add it at 10% to their gas now. which threw the mix ratio way off.

That IS what they tell each other.
+1
 
vasten,
I have a few stihl tools. Its great having 1 fuel mix that works in all.
stihl appears to be using an engineering tool that combines adjacent features when possiable to reduce cost.
have a blower that would not start after a normal shut down.
i have worked on motors for a long time and couldnt figure this one out.
took it in 3/4 torn down. for $25 they told me what was wrong.
turns out that the id of the flywheel is machined in such a way that the keyway is actually part of the flywheel
aluminum flywheel = aluminum key
the key broke allowing the flywheel to rotate slightly on the crankshaft and in turn changed the timing to the point that it wouldnt run
they wanted $85 to fix it
took it home and put it in the vise
carefully filed a new keyway slot into the id of the flywheel
put it back together with a new key
they may have used this type of construction to eliminate a sudden stop if something were to cause a lockup durring
a vaccumn mode should a rock be picked up..............
ran like a top, and still is
should be able to check that out without too much trouble
good luck
rustynut
 
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