# Stihl FS 460 C problems



## damnitchy

Hi. New to forum and first time posting. 

Recently acquired a second hand stihl FS 460. Been having trouble getting it to continue going after it starts. Starts easily however It dies after a couple of minutes of running. I can open the throttle or leave it in choke and it does not make a difference. Opening the throttle makes it die faster. Have taken it to an old school stihl serviceman and he thinks it's the electronics. He does not think its the piston or carb. Any opinions on this? 

It is pretty new and I don't doubt the previous owner when he said it has only done a couple of hours. 

Any one have a similar problem and hopefully a solution? I hope to avoid sending it to a stihl shop as I don't want to increase my mortgage anytime soon. 

Thanks in advance


Sent from my iPhone using Tapatalk


----------



## lone wolf

damnitchy said:


> Hi. New to forum and first time posting.
> 
> Recently acquired a second hand stihl FS 460. Been having trouble getting it to continue going after it starts. Starts easily however It dies after a couple of minutes of running. I can open the throttle or leave it in choke and it does not make a difference. Opening the throttle makes it die faster. Have taken it to an old school stihl serviceman and he thinks it's the electronics. He does not think its the piston or carb. Any opinions on this?
> 
> It is pretty new and I don't doubt the previous owner when he said it has only done a couple of hours.
> 
> Any one have a similar problem and hopefully a solution? I hope to avoid sending it to a stihl shop as I don't want to increase my mortgage anytime soon.
> 
> Thanks in advance
> 
> 
> Sent from my iPhone using Tapatalk


Price a coil then try it . I think it may be the problem it is common I had a few go bad.


----------



## DND 9000

Try to reset the control unit to factory defaults. Remove the cutting attachment and the mounting hardware. Set the choke lever to the start position and start the engine. Let the engine run in this start position for at least 90 sec. After the 90 sec, switch of the engine without blipping the throttle trigger. Now the control unit is calibrated. Maybe this helps you for a better running engine.

If the engine is running after the calibration process let it run four or five times for 30 sec. at full throttle in the cut off range. Between the full throttle phases carry out a few load changes. Between each full throttle phase, let the engine idle for 5 sec. and accelerate again to full throttle.

Let us know if this helps you out.

Kind regards,
DND 9000


----------



## damnitchy

Thanks @DND9000 will try that first before the coil. Will keep you posted. I should also add the unit was probably stored did several years with fuel in it. 

Is electrics a common problem with these newer stihl units?


Sent from my iPhone using Tapatalk


----------



## ANewSawyer

You may have a cracked or damaged fuel line. And the carb probably could use a rebuild if it was ethanol gas.


----------



## damnitchy

Would anyone have the service manual or electrical schematics? 

@ANewSawyer I don't think it would be a fuel line as the serviceman should have spotted it. Hope it does not need a rebuild [emoji29]


Sent from my iPhone using Tapatalk


----------



## damnitchy

DND 9000 said:


> Try to reset the control unit to factory defaults. Remove the cutting attachment and the mounting hardware. Set the choke lever to the start position and start the engine. Let the engine run in this start position for at least 90 sec. After the 90 sec, switch of the engine without blipping the throttle trigger. Now the control unit is calibrated. Maybe this helps you for a better running engine.
> 
> If the engine is running after the calibration process let it run four or five times for 30 sec. at full throttle in the cut off range. Between the full throttle phases carry out a few load changes. Between each full throttle phase, let the engine idle for 5 sec. and accelerate again to full throttle.
> 
> Let us know if this helps you out.
> 
> Kind regards,
> DND 9000


Hi DND 9000 could you elaborate on what you mean regarding cut of range? And carrying out a load change? 

Could fuel type be an issue! Kiwi fuel is rubbish. I once bought a Makita chainsaw that would not go out of the box. Carburetor needed tuning as it was tuned in factory for German fuel. [emoji53]

My better half reckons I'm cursed and should not buy anymore power tools. I smell a conspiracy!![emoji33]

Sorry for the rant. I'm just darn keen to start sorting my land out and this is really getting in the way!


Sent from my iPhone using Tapatalk


----------



## ANewSawyer

What octane rating gas are you using?


----------



## damnitchy

91 on the sign but been told it is lower in reality. Planning on shifting to 97 for all my tools. 

Would it make that much of a difference? 


Sent from my iPhone using Tapatalk


----------



## ANewSawyer

Well, if it was 80 we would have to talk. I use 91 "no ethanol" gas. If there is ethanol in your gas, like there is in most of our gas in the US, I could see it detracting from the octane rating. Still, I would think you should be fine with 91. Unless the station was mixing 50/50 with water.  Sorry, I was trying to help!


----------



## damnitchy

ANewSawyer said:


> Well, if it was 80 we would have this talk. I use 91 "no ethanol" gas. If there is ethanol in your gas, like there is in most of our gas in the US, I could see it detracting from the octane rating. Still, I would think you should be fine with 91. Unless the station was mixing 50/50 with water.  Sorry, I was trying to help!


Any help is welcome and much appreciated! It's all learning for me! [emoji106]


Sent from my iPhone using Tapatalk


----------



## ANewSawyer

One last thought? How old is the gas you are using? It wouldn't cause what you are talking about but it wouldn't help.

Oh and have you tried opening the fuel tank after the unit dies?


----------



## lone wolf

ANewSawyer said:


> One last thought? How old is the gas you are using? It wouldn't cause what you are talking about but it wouldn't help.
> 
> Oh and have you tried opening the fuel tank after the unit dies?


Good possibility and he should eliminate this one first.


----------



## damnitchy

Why would you open the fuel tank? Just in case a vacuum is preventing fuel uptake?

Fuel has been replaced with fresh stuff and 2 stroke mix. Should not be an issur


Sent from my iPhone using Tapatalk


----------



## DND 9000

damnitchy said:


> Hi DND 9000 could you elaborate on what you mean regarding cut of range? And carrying out a load change?



Hi

If you have the engine running full throttle with no load, then you are in the cut of range. The engine speed is electronically limited through the control unit. With several slight load changes I mean that you shouldn`t give the engine all the time full throttle. Sometimes go a little back to half throttle or so and then accelerate to full throttle again.
Changing the fuel can also have an effect. Normally the engines run with pump fuel a little bit richer as with alcylate fuel (like Stihl Moto Mix, Aspen 2 or trufuel) But M-Tronik is able to compensate that, but it can take some time.

If you recalibrate your unit, be sure that your air filter, fuel filter, the fuel lines, the pickup body in the tank and the spark plug is in good condition, too.

Kind regards,
DND 9000


----------



## ANewSawyer

damnitchy said:


> Why would you open the fuel tank? Just in case a vacuum is preventing fuel uptake?
> 
> Fuel has been replaced with fresh stuff and 2 stroke mix. Should not be an issur
> 
> 
> Sent from my iPhone using Tapatalk



Yes, in case the tank vent goes bad and stops letting air into the tank. Thus building up a vacuum.


----------



## kirko

Something not mentioned yet is the possibility of a split primer bulb,, worth a look.
As for fuel I use 98 octane and love it


----------



## damnitchy

Hi fellas. I think it was a plugged injector. It's been cleared and now the bush cutter goes like a demon! Guess that's what happens when you store fuel in it for too long. Good bugger who sorted it for me only charged me $30. And would not take more! So i threw in a box of chocolates. Thanks everyone for your suggestions!! 


Sent from my iPhone using Tapatalk


----------



## backhoelover

here sorry im late on manual glad you got it fixed


----------



## alaskasmitty

I don't understand?? What injector? This has a carburetor yes?


----------



## newforest

Hello, welcome aboard!

Stihl put their 'M-Tronic' electronic fuel control system into their large brush saws, oh some 4-5 years ago now. So they are essentially fuel injected rather than using a traditional carb with user adjustable jets.

Also, it is easy to miss in the light grey font, down at the bottom of every post, almost mixed in with users signature file - the date of each post. These were 3 years old now.

I run an FS 560, it was quite an adventure at first. If you have any questions on one of these saws, I could give one a try; have run brush-saws for many years.


----------



## alaskasmitty

Thanks for the comeback newforest. I knew it was an old thread, surprised to get a reply. This is one our brush saws at the ranch. It has worked well for a couple years now. It seems the spark is inconsistent. It acts like it wants to start when you first choke it, but it wont stay running. Nothing with choke off. Gone through the carb, new fuel, spark plug. Just got a copy of manual from thread, lending some help in diagnosing M-Tronic system. The microswitch on choke doesn't seem to have continuity off or on. its strange it has worked fine then all of a sudden won't start. From what I can tell, to replace fuel solenoid, you have to buy a whole carb. Looks like microswitch is included with wiring harness. Any help or suggestions would be appreciated. They had to take a simple system and complicate it with electronics.


----------



## newforest

There is also essentially a main sensor unit I believe, though this can also be called “The Solenoid” I think. Seems to me would be separate from ‘carb’ unit.

In my experience with early (1980s) vehicle fuel injection systems, the sensors the electronics depend on can be an early fail point as well.

The first step is usually to hook it up to the Stihl software and go from there. My saw was supposedly fixed by a simple ‘Factory Reset’ from within that software, but I suspect the dealer also had to replace something but wouldn’t tell me.

My understanding is that Stihl is quite a bit less guarded about lowly saw owners getting ahold of that software than Husqy is, but to make the connection you need a very expensive black box from Stihl. Whereas Husqy Auto-Tune units use a simple cable, but no one can get their software.


----------



## newforest

P.S. have you checked the muffler screen / spark arrestor? My Canadian friends advise throwing those away, immediately, permanently, on these saws.


----------



## DND 9000

alaskasmitty said:


> The microswitch on choke doesn't seem to have continuity off or on. its strange it has worked fine then all of a sudden won't start. From what I can tell, to replace fuel solenoid, you have to buy a whole carb. Looks like microswitch is included with wiring harness.



It would be good to have it checked with an ohm meter if the target values are reached. (all the cables) You have the service manual, it`s descriped in there how to do. The fuel solenoid valve can be replaced seperately, but a special screwdriver is needed to open that tiny screw. The inconsistend spark could come from a bad or broken electrical connection to the solenoid valve.


----------

