Stihl troubles

[AJahns]

:bang:

I am in some hot water on this one. I’m am in the middle of a large side job (no I am not a pro, yes I have used chain saws for years) and both of my Stihl saws are acting up. My MS250 will not start. I have swapped out the spark plug with a known good one, made sure the fuel is ok... I even swapped out the coil... Nothing...

My MS440 Mag clutch drum froze tight and giving my fits when I attempt to pull it off.

Any suggestions, other than use a different brand from the anti-Stihl crowd or toughski ????ski from the overly-pesimistic-trying-to-be-funny folks.

Is it possible to test coils (easily)? What the frack happened to my MS440 mag? Do these go bad in this manner?

 

[CaseyForrest]

I think we need more information.

Did the 250 all of the sudden not want to start? Was it running ok when you could get it started?

As far as your 440, Ive never heard of that happening. Will the clutch drum turn by hand? Or is it frozen right to the clutch? Once again, did it happen all of the sudden? Did you let it slip to the point where it melted the clutch shoes to the drum?

It is possible to test a coil if you have an ohm meter and know the values you need to be looking for. I dont know what the limitations on a chainsaw coil are, but there are a few here who do.

 

[Kneejerk Bombas]

Your saws didn't die because they are Stihl. Stihl makes greats saws, some OK saws, and some homeowner junk. The saws you have, are among the best saws ever made.
You only need a few things for a saw to run: spark, fuel and compression.
If a saw won't start, pull out the spark plug. If it's wet, it's either flooded (too much gas), or it's not getting spark. Connect the plug to the wire and put the body of the plug against a grounded metal part of the saw and pull the cord. Is there a good spark jumping across the gap?
If it's dry, you're not getting enough fuel. Take off the air cleaner and drip 5 drops of gas down the throat and try to start it. If it fires and runs for a second, you have confirmed you have a fuel delivery problem.
Check the fuel lines and impulse lines ( if there are any) for cracks. Check the fuel filter. If that all looks good, check the carburetor. Inside is a tiny screen that often gets clogged up. There are also two diaphragms that sometimes get tiny cracks or tears. The jets and other tiny passages can get dirt stuck in them.
If you're not comfortable working on carbs, take it to the dealer and let them get it fixed up.

 

[AJahns]

Thanks for your replys CaseyForrest and Mike Maas - now go get some sleep! The trees will be there when you wake up!

Did the 250 all of the sudden not want to start? Was it running ok when you could get it started?

Yes and no... Lately, it would not start that easily... To the point, I thought it was the coil because it is a few years old. So I got a new coil... I took it out again and went to fire it up just to see and it fired up fine. But now it is dead. I will use Mike's troubleshooting info you laid down here, which by the way was very good.

As far as your 440, Ive never heard of that happening. Will the clutch drum turn by hand? Or is it frozen right to the clutch? Once again, did it happen all of the sudden? Did you let it slip to the point where it melted the clutch shoes to the drum?

It is possible to test a coil if you have an ohm meter and know the values you need to be looking for. I dont know what the limitations on a chainsaw coil are, but there are a few here who do.

Regarding the 250, I do have an ohm meter... If you could be so kind, what are the values?

Regarding the 440, the clutch will barely move - to be honest, I am not positive of the parts so I am not sure if it is frozen to the clutch. As I recall, I was cutting a branch and the branch shifted and "bit" the bar and chain. My first reaction was to yank the sucker out... Seeing I am I novice and a numbnut (hey at least I am honest), I bet you I bent the whole assembly. It was hotter than blazes when i pulled it apart after it died (i.e. friction) so I let it cool down. It now somewhat turns with a wrench, but not easily. Nor does it want to slide off...

Keep in mind, when I fire the saw up, it will quickly die after a few seconds, because something is bogging it down.

So dollars to donuts, I broke it that way.

So, at this point, I think I will try to pull the 250 apart to see how the assembly actually comes apart and see if I can pull my 440 off. Along with that, I will use the info to troubleshoot the 250 to see if I can get it to fire.

P.S. Mike, I did not intend to sound like I was down on Stihl. I love them and think they are the greatest thing sliced bread - which by the way neither of my saws can do with a loaf of bread at this time...

 

[CaseyForrest]

Regarding the 440, can you turn the clutch bell by hand? It should spin freely when turned by hand. If not, either the bearing is toast, or the shoes wont let go of the clutch bell. Does it turn over when you pull the rope, and if so does the chain turn when you are pulling on the rope?

 

[AJahns]

Hi CaseyForrest -

Regarding the 440, can you turn the clutch bell by hand? It should spin freely when turned by hand. If not, either the bearing is toast, or the shoes wont let go of the clutch bell. Does it turn over when you pull the rope, and if so does the chain turn when you are pulling on the rope?

I can barely turn the clutch by hand... No it does not turn over because something is holding it back... It sounds like the shoes from what you are describing... Frack! I hope that is better than the bearing letting go...

~A

 

[THALL10326]

Hi CaseyForrest -

Regarding the 440, can you turn the clutch bell by hand? It should spin freely when turned by hand. If not, either the bearing is toast, or the shoes wont let go of the clutch bell. Does it turn over when you pull the rope, and if so does the chain turn when you are pulling on the rope?

I can barely turn the clutch by hand... No it does not turn over because something is holding it back... It sounds like the shoes from what you are describing... Frack! I hope that is better than the bearing letting go...

~A

Have you checked to see if the chain break is activated on the 440?? If not then pull the sprocket off and see whats going on, only one clip to take off.
The 250 sounds likes its flooded. Is there wet gas coming out the muffler, if so its flooded. If not check your fuel line for a crack, look for a wet fuel hose around the carb. Common problem. Have yet to see a coil go bad on a 250 but its possible......................

 

[CaseyForrest]

Chainbrake! Damn, see, thats why Thall is a dealer, and Im not.

 

[CaseyForrest]

Hi CaseyForrest -

Regarding the 440, can you turn the clutch bell by hand? It should spin freely when turned by hand. If not, either the bearing is toast, or the shoes wont let go of the clutch bell. Does it turn over when you pull the rope, and if so does the chain turn when you are pulling on the rope?

I can barely turn the clutch by hand... No it does not turn over because something is holding it back... It sounds like the shoes from what you are describing... Frack! I hope that is better than the bearing letting go...

~A

I didnt mean the crank bearing, just the clutch bearing.

Does the chain turn when you pull on the rope?

 

[THALL10326]

Chainbrake! Damn, see, thats why Thall is a dealer, and Im not.

No biggie, see it all the time. Question to ask is simple, will the 440 start, yes or no. If yes will the motor turn the chain, yes or no. If no pull the chain brake back and then try. Chain turns, brake was on...........................

 

[AJahns]

Hi all -

MS250 update...

I pulled the spark plug and it seemed ok seeing it was not wet.

So I tried your five drops of gas down the throat and pulled it a few times… No go… I even pulled plug and tried five drops and nothing. For giggles, I sprayed some starting fluid in the throat and tried again… Nothing… I also pulled the plug and sprayed a quick shot in and put the plug back in and tried. Nothing.

At that point, I thought I did not have any spark… I tested the spark with your idea above and it indeed had a spark jumping across.

I am fairly frustrated and pissed at this point seeing it was well over 100° F.

After some calming down, a large glass of water, I went back at it… Even though it still did not make sense…

I then checked the fuel filter and fuel line that feeds the carb. Everything looked fine, no cracks etc. I also could tip the saw over a bit and had fuel come through the line – So I am thinking it is fine with respect to the fuel delivery.

Next, I pulled the carb. The tiny screen was ok and the two diaphragms seemed ok with no noticeable tiny cracks or tears. The jets and other tiny passages seemed fine… I cleaned everything and put it back together and installed the carb.

Thinking I have eliminated all variables and the sucker would start, I tried. Nothing. I then did the above five drop routine and again nothing.

At this point, I am hot tired and still without a saw. So I calmly put it down and put it back into its carrying case and through it out on the freeway and bid it farewell.

Just kidding on the freeway crack… :biggrinbounce2: I did put it away… I can only take some much troubleshooting without positive results.

 

[Dadatwins]

On the 250, if you have checked fuel and spark with positive results next check rubber carb boot and make sure it has not ripped. Next start checking compression on the piston. If you don't have a testor, hold the saw up by the pull cord and it should not drop. If it does, scored, bad piston or rings might be suspect. Pull the muffler and take a look at the piston and rings and cylinder walls, check for scratches, ect. Next place to look for a no start is crank seals, you can look at both sides and sometimes see the seal blown out around the crankshaft. Have to pull the flywheel and clutch to see both sides.
On the 440, sounds like chain brake locked up to me also, pull cover over oil pump and see if it is disengaging with handle, if brake is not locked pulling this cover will give you more access to clutch drum also. good luck.

 

[Kneejerk Bombas]

Low compression is possible, good call Dada.
I don't know if I made it clear, but you need to look at the plug for flooding right after attempting to start it. The starting fluid is a bad idea, it doesn't have any oil.
I've worked on saws that had spark, but it was a weak yellow color. Compare the spark to a working motor to get an idea of what it should look like.
If you have good spark, and it won't fire on some fuel dripped in the carb, the only other thing I can think of is spark timing. Could the flywheel keyway have stripped?
It's not a carb problem or it would have fired on fuel you dripped in. The same with carb intake boot, seals or other air leaks.
Whatever the problem, it's not your typical, simple, homeowner problem. Have you tried the Chainsaw section of this site? It might yield better responses. There are a few fart smeller's... I mean, smart fellers there.
Good luck, I know the frustration of working on something without results. This computer I'm typing on has almost been thrown though the picture window a time or two.

 

[Marco]

You may want to take a good hard look at the brass check valve/jet thingy in the carb. You can drift it out and get a new one in pretty easy. I have a Ms250c here with the primer bulb and Chinese carb that replacing that seemed to help on, can't get the owner of it to take it out and try it as he is having to much fun with the Poulan I sold him, so don't throw the saw and case away, you can get something else to fit in the case.

 

[Kneejerk Bombas]

Again, I don't think it's a carb issue or it would have started on the added fuel, unless it's flooding, in which case the plug would be wet.

 

[antigrassguy]

My 2 cents, but could the spark arrester be plugged on exhaust? Check the screen. Hoping for a simple fix for ya.

 

[Tank]

I have an 250 also and had some trouble figuring out the technique for starting it. After similar frustration, I brought it back to the dealer. He said it was flooded. He promptly to it out back, put it in the on position (no choke), held the throttle trigger open and gave numerous pulls (approx 20). Eventually it started, then he explained precisely how to start it. From a cold start, put it in the choke position and give 3-4 pulls (no throttle). After pull number 3 or 4, you should hear a quick fire. As soon as you hear that, move the switch to the open position and it should fire up in 1 or 2 pulls. It now works everytime for me no problem. If you have it in choke and give more than 3-4 pulls it will flood every time. Yes, they are a little sensitive but once you figure it out they work great.

 

[046]

no BS, I had a stupid attack and didn't check break release on my 046. thought I had a frozen clutch

 

[lazeyjack]

testing your coil

[ place your ohm metre on 20k, put one probe on the block, other inside plug lead end, resistance 3 -15, no reading dud coil, break in circuit high reading poor connection where lead enters coil
Now never pull a carb to bits before you have set reset the low speed needle to factory setting and started over to try start the thing, , assuming of course your spark is ok, for some reason, idle and power jets do need adjusting from time to time
the coil on my Husky just packed a sad in the middle of a job, one minute was ok, next I stopped top refuel, would not start or even fire
Anto Stihl crowd,? as early as 1967n was using one to clear fell native in NZ, was a great machine husky 268 with 20inch bar is ok,left it outsidemonce on my farm, could,nt find it for 6 months, new gas, fired up no trubbs

Any suggestions, other than use a different brand from the anti-Stihl crowd or toughski ????ski from the overly-pesimistic-trying-to-be-funny folks.

Is it possible to test coils (easily)? What the frack happened to my MS440 mag? Do these go bad in this manner?[/QUOTE]

 

[lazeyjack]

as you can see I spell well too!! wee engines not really my bag, was Cummins employee before started yachtbuilding