031av questions

[sawjo]

I have been fighting with an older Stihl 031AV. It will start and run to WO and then die. I have been through the fuel system and now I am on to the ignition. (150 lbs of compression, by the way) I cleaned and reset the points and the old Bosch WSR6F plug will show a bright yellow spark for 1 or two pulls and then drop to a vey weak and tiny blue spark. I have done the searchs on this and have seen the suggestions for the Atom module etc. Do you guys think the plug maybe just bad? I have no replacement tonight to test with. Do I need to split the fuel tank to remove flywheel? It looks like I am not going to get away without buying the work manual for this saw.

 

[Rotax Robert]

Pull a plug out of your mower, weed wacker, etc.

Rotax

 

[daemon2525]

Most will not agree, but shine the flywheel (with sandpaper, steelwool whatever) as best you can, and then position the coil as close as you can without it touching.

 

[daemon2525]

Oh yeah, and get a new plug.....

 

[Rotax Robert]

I shoulda said borrow a plug out of your mower, weed whacker, etc. only to check for spark. Don't install it, but I am assuming you already know that.

Rotax

 

[Lakeside53]

You most likely have a bad condenser. No, you do not need to split the fuel tank. There is a screw on the chain cover side that release the entire tank assembly.

If you are going to convert to electronic, you need to either get the correct flywheel or reposition the existing flywheel. There are several old posts on this.

 

[ozflea]

Sounds like it has an air leak or maybe might need a carby kit.

I can't see how shining up the flywheel helps unless your into show and shine,
but check for airleaks or busted hoses.

Mc Bob.

 

[Lakeside53]

Sorry, got distracted and only posted about the ignition: On the fuel side issues:

Check the impulse hose where it connects to the carb - they often fit really loosely and leak. Also, pop the carb pump cover and see if the inlet screen is blocked. A lot of the 031's I see still have the original (!) fuel filter and it's disintegrated into the carb.

 

[Fish]

Remove the starter assembly, and look at the top of the flywheel.
See if it has the two white plastic access plugs, and if it does, clean
and regap the old points, set them at .016
You should see some improvement, if so, replace the points and condenser

 

[retoocs555]

I've had 2 031's that would run like that because of a torn carb boot.

 

[sawjo]

Thanks guys, will recheck all of the above. Have a nice holiday weekend!

 

[McC]

One of the 2 031's I recently converted to electronic came back this week. I should have worked on it a little longer. It seemed to run a little lean at times, after a carb rebuild, but the guy just wanted it running again for a backup saw. I thought the seals might be getting a little worn. I knew the impulse line and carb boot were good. He ran less than a day, and it wouldn't stay running for more than a few seconds, starving for fuel. I had the metering lever set level with the top of the casting, like most other carbs, but it was sucking the chamber dry before opening the needle. I bent the lever so it was over the casting a bit, and it runs like a champ. I never did anything to the flywheel on either of these 2 saws. They run great.
Scott