Stihl O46 Stalling ?? Service manual ???

[oliffers]

Any clues why my Stihl o46magnum would be stalling. Cut a few logs and it wants to stall all time. It has had a new fuel filter, new ngk plug, new air filters, and new clutch springs installed.
Also chasing a service manual please !!!!!!!
Oliver

 

[West Texas]

I don't think that's too unusual, especially in hot weather. It could be seals, etc. but I adjust the "L" jet for easy starting, then adjust the "LA" a little on the fast side, as most saws will 'slow' down once they get hot. Then adjust the "H" jet for best high speed performance in the cut. That means a slight four cycle sound at wide open throttle, that will smooth out once the saw is in the cut.

Madsen's has an excellent article on carb tuning; but, the above is my simplification of it for use in the field.

Assuming its not the seals, I'd say adjust the "LA" when it gets hot and see if that doesn't solve the problem.

 

[oliffers]

Thank you West Texas!
But its also stalling even when cold if that makes a difference ????
Oliver

 

[Lakeside53]

It's probably a tad rich on the L screw. Try turning it an 1/8 turn clockwise.

 

[Ozzie1957]

Oliver,
I had/have the same problem from when I bought mine new.
First make sure you have the latest tank vent setup.
Well... at least the revision (11.2000 tech bulletin) just before they changed to the new 460 style gas tank setup.
You could have a vacuum developing in your gas tank causing a starving for gas issue.
Try this after a stall.
Open your gas cap and listen for a hiss from a vacuum sucking in air.
If that's it then you need to address that issue.

Second issue was the low speed adjustment (L screw).
I ended up removing the screw stops on the L and H screws.
I left the H screw at the stock setting and then adjusted the L screw to about 2 1/2 to 3 turns open to stop it from stalling after a cut.
3/4 turn open is all the stock screw stops will allow.
That sure seemed waaaaay beyond normal to me so I told my local Stihl dealer and he said that didn't surprise him at all.
I thought what the _ _ _ _?
But whatever....it runs now.
Also, this was after disassembling the carb and dip/soak cleaning twice.
Must be some sort of internal flaw in the carb possibly.
Now keep in mind I'm not saying this is what you should do.
This is what worked for my saw.
I don't like going outside the recommendations of the manufacturer....AT ALL!
I am still not comfy with that L screw setting....but....it worked.

As far as the service manual, this link will get you to the bulletins.
Just change the xx to tt.
And then you can request that he post the service manual.
He used to have all the manuals posted but I can't find a link to them on his site.
The bandwidth was probably costing him a fortune.
hxxp://www.giftsofwood.com/stihl_info TI 046.htm

Good Luck!
Ozzie

 

[Lakeside53]

Oz - Never seen a 460 carb that needed 2 1/2 turn on the L to idle unless it has an air leak in a seal... The 460 carb is a 1 turn out for standard settings. I take off the tab also, but it's still within an 1/8 of a turn from 1 out.

Did you pressure and vacuum test the saw?

 

[oliffers]

pressure and vacuum test the saw?[/

Oz - Never seen a 460 carb that needed 2 1/2 turn on the L to idle unless it has an air leak in a seal... The 460 carb is a 1 turn out for standard settings. I take off the tab also, but it's still within an 1/8 of a turn from 1 out.

Did you pressure and vacuum test the saw?

Being a newbie to chainsaw game How do you pressure and vacume test the saw.
Still a service manual would be nice for a 046 magnum.
Thankyou -- Oliver

 

[lostone]

I had the same problem with mine as well, I could make a few cuts then it would stall and I couldn't get it to start again until after it cooled down. I replaced the tank vent to the newer style and it didn't help it, I ended up rebuilding the carb and it runs great now. When it had the problem everything would be fine I could start it and let it set there and idle for 15 minutes no problems, I could hit the trigger and everything seemed fine it would only act up after I had it under load for a few minutes making cuts.

 

[Ozzie1957]

Lakeside,
No I didn't have a pressure or vacuum test done.
I guess I assumed a new saw would not need those tests.
But I guess quality control could have missed something.
The dealer here want's $30 to $60 (depending on how long it takes) to do the tests.
I will consider that.
Additionally, the symptoms I and other 046 owners seem to have are not the symptoms described in the manual that would require a pressure/vacuum test.
The manual mentions erratic idle or not being able to set it at all and un-smooth transition from idle to part or full throttle.
The symptom I had/have is the saw runs perfect in every instance until you let off the throttle after cutting through a good size hardwood log then it simply stalls.
You can try to give it some throttle but it's as if it's out of gas.
It would probably run through a full tank of gas just fine if it was run at half to full throttle all the time.

Oliver,
Did you go to the gifts of wood website and request the manual?
If not, go into Private Messages in your User CP and send me your email address.
I can try to send you a copy of the manual (a zipped PDF file) if your email service will accept a 9 MB file.

The vacuum test is covered in the manual but it would probably be a lot cheaper to have the dealer do it than to buy the equipment for a one time test on your own.

Lostone,
What parts did your carb rebuild kit come with and did you use everthing?

Thanks,
Ozzie

 

[Lakeside53]

The reason I asked about the pressure test is that if you need 2 1/2 turns out to idle and overcome your other problem, you are likely either sucking air somewhere or have a blocked carb low jet etc. Non-standard carb setting are a really good indicator of other problems.

 

[lostone]

Lostone,
What parts did your carb rebuild kit come with and did you use everthing?


Ozzie

Typical rebuild kit, it had the needle, lever, diaphrams, gaskets, screens and welsh plugs. I used everything but the welsh plugs (I took a chance on them not leaking)

 

[Ozzie1957]

The reason I asked about the pressure test is that if you need 2 1/2 turns out to idle and overcome your other problem, you are likely either sucking air somewhere or have a blocked carb low jet etc. Non-standard carb setting are a really good indicator of other problems.

I agree.....something is just not right.
I would have to go with the "blocked carb low jet" at this point.
Whatever it is it won't dissolve using the carb dip and soak in the solvent method.

Keep in mind that it does not take 2 1/2 turns out to idle.
It idles perfect and runs perfect regardless of where the L screw is set.
It simply stalls when releasing the throttle after a 15 second full throttle cut.

 

[Lakeside53]

I called my Stihl Technical rep and asked him if they had had similar reports anywhere.

There are a few cases of this happening, mainly on earlier production units.

1) Boot collapse. The boot when subjected to the sudden vacuum of a closed throttle from full power can collapse momentarily. A stiffer boot was put in production to overcome this.

2) The chrome plating on the the metering valve seat wears off or becomes detached. This allows the metering needle to leak. If the seat looks like "brass" you have a problem.

3) Earlier coils could misinterpret the timing and actually try to run the saw in reverse when the throttle was suddenly closed.

 

[Ozzie1957]

Lakeside,
After reading the melted 066 piston thread, I came back to this one and wanted to be clear on something.
When you mention "earlier production units", what time frame would that be?
I bought my 046 new in early 2001.
So I think it has most of the factory "Fixes".
Unless you're Technical rep was talking about early 460's.
Which my 046 would be an early 460 I guess.

Thanks,
Ozzie

 

[Lakeside53]

Yes, the problems were framed around early '460". Not sure if it extended back to the 046, but they are worth checking out. My contact is on vacation for the next two weeks so I can't get any clarification right now.

You can check for boot collapse by vacuum testing the saw and just watching the boot.

The carb seat can be checked by a simple pressure test via the fuel line inlet and visual inspection.

 

[Ozzie1957]

Hey Lakeside,
If you get a chance to talk to the Stihl Tech rep (that's probably swamped after his vacation), could you ask him to clarify if the 3 problems mentioned apply to an early 2001 046?
I would be interested in the part #'s for the stiffer boot (item 1 below) and the coil (item 3 below).
I think the chrome plating on the carb should be easy enough to spot.

I have (I think) all the TSB's for the 046 and 460 but I don't see any mention of these problems in any of them.
If there is a couple TSB's I'm missing, they would probably have the replacement part #'s.

If anyone has the TSB's if they exist, could you provide me with a link?

Thanks,
Ozzie

_______________________________

I called my Stihl Technical rep and asked him if they had had similar reports anywhere.

There are a few cases of this happening, mainly on earlier production units.

1) Boot collapse. The boot when subjected to the sudden vacuum of a closed throttle from full power can collapse momentarily. A stiffer boot was put in production to overcome this.

2) The chrome plating on the the metering valve seat wears off or becomes detached. This allows the metering needle to leak. If the seat looks like "brass" you have a problem.

3) Earlier coils could misinterpret the timing and actually try to run the saw in reverse when the throttle was suddenly closed.

 

[Lakeside53]

There are no new part numbers for the boot or tsrs... Stihl doesn't always publish in-production corrections if it affects only a small set of users or a small set a few years after production.

You should be able to see the boot problem by vacuum testing. If it collapses more then "normal" when hot you can just replace it with a new part. Obviously you don't want to buy old stock though...

The coil... what is the part number of the coil you have (should be on the side of the coil)? The latest version is the 1122 400 1314, which is the same coil used on the 066, MS650, MS660 and others... but if you look at the 066/660 coils over the last 10 years, there have been many other types. I doubt if the coil is your issue here, but if you can borrow another, it's worth trying.