Stihl ms 250 problems please help

[gazzapowells]

Hello 2 you all.....

 

thanks in advance for your help

 

i have a problem with my MS 250 when i start the saw it revs up fast then just cuts out, i dont know much about chainsaw so please can someone give me some help

I did a compression test and it was ok i think? it was reading 130 psi

 

thanks

[Mesterh]

Hi,

 

Could be quite a few different things tbh.

130 sounds a bit low tbh I think it should be more around the 150 mark.Does it 'feel' like it has good compression? ie if you pull the starter cord does it have noticiable tough spots rather than pulling uniformally (if you can understand that )

 

 

Check fuel line for splits,cracks.

Check boot between carb and cylinder for cracks.leaks etc.

Make sure choke aint sticking on or off.

If none of above then prob a carb fault but you need to be a bit more explicit with your description.Does it tick over?

[Husqvarna King]

air filter??

[Husqvarna King]

or...you could paint the saw all orange and pretend that its a "propper saw"

[Dean Lofthouse]

It does sound like a split fuel line .

[DriveLink]

Is the choke sticking on? That would cause the saw to start, then cut out due to the fuel:air mix being rich.

[gazzapowells]

have looked at all fuel lines and they ok... choke is not sticking compression feels good when you pull start cord... any more ideas please?

 

how easy is it to rebuild the carb?

 

thanks all

[gazzapowells]

feels like it has good compression i start saw as normal with choke on. choke off start again and its revs up very high and just cuts out...

 

 

 

 

Hi,

 

Could be quite a few different things tbh.

130 sounds a bit low tbh I think it should be more around the 150 mark.Does it 'feel' like it has good compression? ie if you pull the starter cord does it have noticiable tough spots rather than pulling uniformally (if you can understand that )

 

 

Check fuel line for splits,cracks.

Check boot between carb and cylinder for cracks.leaks etc.

Make sure choke aint sticking on or off.

If none of above then prob a carb fault but you need to be a bit more explicit with your description.Does it tick over?

[Dean Lofthouse]

You might do well checking the carb diaphrams haven't gone hard or stiff or maybe the fuel gauze in the carb is partially blocked.

 

I wouldn't of thought the diaphrams would be hard on an MS unless it has been stood for some period of time without being used.

[DriveLink]

feels like it has good compression i start saw as normal with choke on. choke off start again and its revs up very high and just cuts out...

 

How high is "high" - I mean, is it full revs, or the same sort of thing that you get on 1/2 choke?

 

When you start the saw - full choke, the saw fires and dies. Then do you move it to half choke, start it - at this point it'll rev high, but squeezing the throttle briefly should return it to idle.

 

What happens when you just blip the throttle? How long does it take before it cuts out?

 

The MS250 has that sort of semi-circular air filter that just clips on doesn't it? I can't remember about the carb on this saw - but could it be that the atmospheric vent on the carb is blocked?