Stihl MS361 Woes

[Treerover]

Hellllllllllllp.

I’ve recently rebuilt one of my long since retired Stihl MS361’s out of old bits (due to some delightful individuals stealing all my saws last year)

 

It fires up a dream, sounds right, runs and cuts like a beauty.......for about 3-5 minutes and then it dies.

It’s almost as if it’s flooding mid use.

Its not the tuning and I’ve replaced the carb for another one (old one) but it still does exactly the same thing.

I’ve put a new diaphragm kit in and carb cleaned the living be-Jesus out of it but it still dies after a few glorious confidence teasing minutes .

 

Any clues chaps and chappettes as I’m flummoxed on this one ?

[Stubby]

5 minutes ago, Treerover said:

 

Hellllllllllllp.

I’ve recently rebuilt one of my long since retired Stihl MS361’s out of old bits (due to some delightful individuals stealing all my saws last year)

 

It fires up a dream, sounds right, runs and cuts like a beauty.......for about 3-5 minutes and then it dies.

It’s almost as if it’s flooding mid use.

Its not the tuning and I’ve replaced the carb for another one (old one) but it still does exactly the same thing.

I’ve put a new diaphragm kit in and carb cleaned the living be-Jesus out of it but it still dies after a few glorious confidence teasing minutes .

 

Any clues chaps and chappettes as I’m flummoxed on this one ?

 

Tank vent blocked and pulling a vacuum ?

[Ratman]

You getting a vaccum in your fuel tank? Breather issues?

[spudulike]

But do they know where the breather is Hidden behind that plastic cover where the top handle joins to the side of the fuel tank!

It is the most likely problem but the coils on these machines can also go wobbly stopping the engine making full revs!

[Stubby]

6 minutes ago, Ratman said:

You getting a vaccum in your fuel tank? Breather issues?

Are you cribbing my test sheet ? ?

[Ratman]

Are you cribbing my test sheet ? [emoji16]

[emoji1391]‍♂️

[Treerover]

But do they know where the breather is:sneaky2: Hidden behind that plastic cover where the top handle joins to the side of the fuel tank!
It is the most likely problem but the coils on these machines can also go wobbly stopping the engine making full revs!

Hiya Spudzo, yes I’ve checked the secret square but what exactly should I be checking for as nowt seems bust internally .
No vacuuming/pressure from tank audible when the cap is released .

I’d think if it was the magneto then it wouldn’t run perfectly for the 3 minutes would it ? [emoji848]
Still baffled

[billpierce]

Hiya Spudzo, yes I’ve checked the secret square but what exactly should I be checking for as nowt seems bust internally .
No vacuuming/pressure from tank audible when the cap is released .

I’d think if it was the magneto then it wouldn’t run perfectly for the 3 minutes would it ? [emoji848]
Still baffled

Yes, the coils are wierd. My 361 was a right twat. Working ok then cutting out at random. Usually restarted fine. Next time it cuts out check the spark immediately. Spud replaces replaced my coil after I had gone mad trying to part mine and rebuilt the carb about 14 times. It has recently gone again, this time it seemed to advance the timing and became nearly impossible to pull over. Wasnt going to spend a fortune on an OEM coil as the last one lasted 2or 3 years. Have replaced with cheapo Chinese one a few months ago. Seems fine for now.

Not saying this is defo the bother, but my 361 drove me mad and turned out to be an unpredictable coil

[spudulike]

How about running it until it flubs, keep it running, put it on its side, loosen the fuel cap and see if it suddenly clears or if it still has the issue - that is probably the easiest for you. The tech way is to remove the fuel filter and carb then pump the air out of the tank through the fuel line with a vacuum pump and see if air is replaced through the breather.

There is usually a load of woodchip under that little cover and it blocks the breather,

You can double check the coil to flywheel gap or reduce the gap right down to the thickness of A4 paper and see if it has any effect.

[Treerover]

Yes, the coils are wierd. My 361 was a right twat. Working ok then cutting out at random. Usually restarted fine. Next time it cuts out check the spark immediately. Spud replaces replaced my coil after I had gone mad trying to part mine and rebuilt the carb about 14 times. It has recently gone again, this time it seemed to advance the timing and became nearly impossible to pull over. Wasnt going to spend a fortune on an OEM coil as the last one lasted 2or 3 years. Have replaced with cheapo Chinese one a few months ago. Seems fine for now.

Not saying this is defo the bother, but my 361 drove me mad and turned out to be an unpredictable coil

I now have a third child Bill due to the unpredictable nature of a faulty coil so yes I can attest as to their less than infallible reliability !!!

You suggest checking the spark plug ?
I’m guessing if it’s the coil then the plug would be wet through ?
I’m still awaiting the breather detail though as mentioned by the Spudmeister as it’s such a seemingly simple part I think I may be ignoring something else that may be staring me in the faeces .
(That and breather checking is cheap, magneto purchasing slightly more expensive) [emoji857]