Stihl MS261 backfiring, running backwards and generally misbehaving

[spudulike]

My favorite is when a customer says "I have tried everything" and gets my response "what can I do then if you have done everything to fix it"?

Usually better when no one has messed with it!

 

[pleasant]

Yeah.....this one's a classic. Think about what you are actually saying to the person you really need help from before you use this one, but I bet a load of you do!

 

'I've been everywhere.....you're my last chance'

 

Think about how that sounds for a moment. I hear that a lot and people really don't realise what they are saying.

[AWG81]

Thanks both. Yeah, it's running with the aftermarket coil. I have another one I can try. The decomp is genuine Stihl which I put on so that should be fine.

 

It certainly does seem like it's flooding the chamber.

 

I appreciate it's difficult to diagnose without seeing the machine. The suggestions here are super helpful. I'm sure I can get this thing sorted eventually and I will have learnt something along the way.

 

Actually maybe the lesson is "don't buy cheap saws off eBay in the first place"...

 

[spudulike]

Try the original OEM coil, it may well work and sounds like the start up ignition timing of the aftermarket coil is causing the backfire and the decomp valve to pop out.

Flooding generally means the saw may pop but generally stops it running in my experience. 

Try the easy most likely stuff first, if the saw does idle and rev out once started, it is probably unlikely to be carb related.

[AWG81]

Just wanted to update on this - I swapped out the coil for another one and it seems to be working pretty good. I fixed the switch issue too. Used it all day today for work, and mostly all good after a bit of carb adjustment. Does seem to very occasionally backfire, and doesn't like to start with the decomp valve in so it's not perfect, but usable which is a big improvement on where I was. Thanks for the advice here, much appreciated.

 

Cheers!

[spudulike]

Thanks for letting us know, it shows we aren't all losing it and barking mad.....well not too much.

[pleasant]

Well done. 👍

[Dan Maynard]

2 hours ago, AWG81 said:

doesn't like to start with the decomp valve in

I've got a ten year old 261, I suggest to never press the decomp button.

[Wonky]

I’ve learnt not to use the Dylan button on all my saws.🤔

 

think about it 🤪

 

 

 

Edited May 18, 2023 by Wonky

[Dan Maynard]

Like it on my 461 though