Motorproblems on Stihl MS 250 C

[Penge58]

Hello guys

I have a motorproblem on my Stihl MS250 C
It starts but will not run on idle or when I try to speed up.
After the winter I sent my chain saw for service.
The service guy said that the saw would not run on idle and he had measured the compression and found a damaged cylinder that caused bad compression.
I took the saw back and replaced the engine myself following the instruction on a youtube video.
I also cleaned the carb. Took it apart and cleaned the carb house in an ultra sound washing machine.
I also replaced the fuel filter.
Then put it all back together again but the same problem is still there. It starts but dies quickly on idle or if I try to speed up.
I then set the carb adjustment back to factory settings but that did not help.

Any advice you have would be appreciated.

Thanks a lot.

Petter

 

[HarleyT]

A good thing to look at is the impulse line. It may not be attached to one of the nipples. Usually the orange one.

 

[Penge58]

Thank you Harley
I will check it.
What does the impulse line actually do ? How dows it work ? It goes from the motorblock into a yellow nipple ?

Thanks

 

[MartDalb]

Impulse hose feeds the carburator to keep idle. It's rather simple to replace it on the ms250, granted you have some good pliars.

We need pictures!

Also, which carburator model is on your saw? zama or walbro?

I had a ms250, rescently, with a zama carb, that would die instantly when given gas, simple fix was adjusting the needle setting inside the carburator.

 

[HarleyT]

Here is the "nipple"........
I circled it in purple.

 

[HarleyT]

To look at the nipple, take off the pull starter, you can reattach it this way with hemostats and the like.

 

[sean donato]

When you cleaned the carb did you install a new kit in it or reuse the old stuff? Did you set the needle height correctly, if you did install a new kit?

 

[HarleyT]

I don't need to circle these in purple,
oddly......

 

[HarleyT]

Still working on the "taking off her starter" joke......

 

[HarleyT]

Well he wanted more pics.....

A new carb from your Stihl dealer is pretty dang cheap..
1123 120 0603 CARBURETOR (MS250) $22.67

 

[Penge58]

Hello Harley

I have been busy with other stuff so I haven't been able to reply to you.
And I strange enough did not get any notice about your new posting so thank you for all your postings.
My carb is a ZAMA type.
I have disassemblied the saw again now to check the impulse line. I wanted to ask were the nipple for the line was but then you already showed me that
Great. I will check if its connect correctly.
But this is a "blind" nipple ? Does not go anywere ? So how is this working ? Anyway. I will check it.

No I did not replace any parts. I used the old parts.
However I have ordered a new carb and installation kit through ebay but there was some delivery time.
The H and L needle is set according to fabric settings even I used the old carb.
I have seen on you tube were they demonstrate the H and L settings and those chain saws are running even if the needels are in either end of the turn.

You mention hemostat.
What is that ?

Petter
Norway

 

[MartDalb]

Impulse hose goes to impulse nibble that leads to the carburator, and matches the carburators impulse "inlet".

Pliars, hemostat,
I use these...dirt cheap from ebay.

 

[RED-85-Z51]

Impulse line feeds pulses in air pressure to the pump side of the carb to act as a pump to draw fuel in.

Sent from my LM-G820 using Tapatalk

 

[Penge58]

Yes the impulse line was connected to the nipple and I see how that nipple is working now.
Maybe the nipple itself need to be cleaned. Compressed air ?
The hose might have slipped off the connection to the motor block though. No guarantee for that.
The only part i see that I maybe should be replaced is the one shown on the picture here.
However I cannot see how that gives any leakage to the carburettor.
What do you think ?

 

[MartDalb]

Yes the impulse line was connected to the nipple and I see how that nipple is working now.
Maybe the nipple itself need to be cleaned. Compressed air ?
The hose might have slipped off the connection to the motor block though. No guarantee for that.
The only part i see that I maybe should be replaced is the one shown on the picture here.
However I cannot see how that gives any leakage to the carburettor.
What do you think ?

Yeah, gaskets are cheap and should be replaced looking like that.

I had a MS250 once, did all the works on it, would not idle, or only idle insanely high rpm when turning the L screw.
Ended up cleaning the carb a few times, and finally, apperently did it correct on the last attempt, I am pretty sure it was the impulse opening on the carburator that had microscopic dirt on it . Carbs are sensitive, like women I guess.

 

[MartDalb]

Norway.... Im in Denmark here.

How far up Are you?
I have a spare one right here

 

[Penge58]

Yeah, gaskets are cheap and should be replaced looking like that.

I had a MS250 once, did all the works on it, would not idle, or only idle insanely high rpm when turning the L screw.
Ended up cleaning the carb a few times, and finally, apperently did it correct on the last attempt, I am pretty sure it was the impulse opening on the carburator that had microscopic dirt on it . Carbs are sensitive, like women I guess.

I will get a new gasket tomorrow.
The Stihl dealer and service centre is just 5 minutes walk from here
I will clean the nipple and carb carefully with compressed air and go through all the hoses.

I will let you know how that goes.

Thank you so far

Petter

 

[Penge58]

Norway.... Im in Denmark here.

How far up Are you?
I have a spare one right here

heheh...I am just on the Norwegian side of the Color Line ferry that goes to Hirtshals

 

[MartDalb]

Thats around Kristianssand then? If im not mistaken.

 

[Penge58]

Ahhh....I forgot about that ferry.
No....I live in Sandefjord which is the closest town to Larvik were the Color Line Super Speed goes from