Stihl MS 250 shutting down

[Country bumpkin]

Just repaired one for a guy. It was the coil. Get a oem. You can go used route also on flea bay cheap.

 

[C George]

Ign coil / module starting to fail

 

[NuclearNick]

OK finally getting back to this. Darned day job keeps getting in the way.

I basically took this whole saw apart, cleaned up every part I could without taking the head off. Did a carb rebuild (all new gaskets from kit), replaced fuel line and impulse line, new air filter, new plug, and replaced coil with new OEM coil. Checked / cleaned spark arrestor. Also replaced oil suction line, drain plug, and both gas and oil caps.

Saw starts just fine, seems like it's ready to run, but as soon as I try to give it some gas it dies almost immediately. It runs OK at low idle but sounds like it's hunting abit. Just can't give it any gas or it just shuts down.

thoughts?

 

[J D]

Sounds like you have a problem with the H circuit, probably blocked somewhere or the adjustment needle may be set wrong or damaged.
Did you pull the welch plug when you cleaned it? What solvents did you use? Did you put compressed air through it?
The main nozzle check valve (that lets fuel into the venturi) could also be the cause if it's damaged

 

[SteveSr]

OK finally getting back to this. Darned day job keeps getting in the way.

I basically took this whole saw apart, cleaned up every part I could without taking the head off. Did a carb rebuild (all new gaskets from kit), replaced fuel line and impulse line, new air filter, new plug, and replaced coil with new OEM coil. Checked / cleaned spark arrestor. Also replaced oil suction line, drain plug, and both gas and oil caps.

Saw starts just fine, seems like it's ready to run, but as soon as I try to give it some gas it dies almost immediately. It runs OK at low idle but sounds like it's hunting abit. Just can't give it any gas or it just shuts down.

thoughts?

I had a Stihl 021 do just this. It would run right one time and not the next. The cause was a non-repairable carb fault... The main nozzle check valve was stuck closed. When this happens the saw will idle all day long but can't transfer to the high circuit. Time for a new OEM carb.

 

[NuclearNick]

I had a Stihl 021 do just this. It would run right one time and not the next. The cause was a non-repairable carb fault... The main nozzle check valve was stuck closed. When this happens the saw will idle all day long but can't transfer to the high circuit. Time for a new OEM carb.

We’ll that’s about the only part I haven’t replaced on this thing. I’m about $80 into this effort, will probably try your advice so I have a backup saw.

In the meantime I pulled my Dad’s old 028AV Wood Boss off the shelf, which started on the 2nd pull after sitting unused for 5 years. Its a heavy beast, but ran all day long without a hitch.

 

[NuclearNick]

@SteveSr that did the trick. Dropped a new OEM carb in it, and the saw fired up perfectly and ran like a top.

All total I put over $120 of new parts into the saw. Had I known how much money I would spend maybe I'd have just put that towards a new saw. But if it runs well for another few years I'll call it a win.