Stihl 031av Ignition Problem

[KennyPete]

I seem to be having an ignition problem with my 031av. Saw starts fine, runs good for about 5 minutes, then dies. Will not start again until it cools off. I disassembled it, figuring I needed to switch it over to an electronic ignition module. I pulled the flywheel and discovered that the condenser was loose and there was a small bare spot on the kill wire. I cleaned everything, secured the condenser, repaired the bare wire, and put the saw back together, hoping that would fix the issue - no such luck. Same thing - runs GREAT when cold, as soon as it heats up it dies.

On another thread here, I came across this

"Problems with the ignition coil can make an engine impossible to start when warm (or even stop running when it warms up), apparently this happens on motorbike engines quite often and is caused by a break in the HT coil.

A carbon track forms inside the coil where the wire is broken. When the engine is cold the carbon track has a low resistance and it conducts well enough so the spark is strong enough to start the engine, when the engine is warmer the track resistance is greater and the spark less strong. This problem gets worse over time as the carbon track gets bigger and bigger, the only remedy is to change the coil or electronic ignition module."


Is there a way I can repair this line in the coil? Would it be as simple as just replacing the spark plug wire, and can that be changed? I havent knocked the saw apart again yet to look in to it. Thanks in advance for your help.



TL/DR
Disassembled and cleaned the saw
Cleaned the carb
Replaced the plug
Pulled the flywheel, secured the loose condenser, cleaned & set the points, and reassembled.
I had a small bare spot on the kill wire that I fixed with adhesive heat shrink
Problem seems to be a carbon track in the coil, though no marks on the plug

 

[MnSam]

On points ignition 031's typically the coil doesn't fail, the condenser is the culprit. The condenser can be replaced with a Wima capacitor (my favorite method, but requires flywheel removal), or the condenser and points can be bypassed and an aftermarket ignition module/chip installed (doesn't require flywheel removal, but sometimes requires a timing adjustment). There is a ton of info on the 031 ignition here. Use the search function and read for hours.

 

[MnSam]

... given your fuel delivery system is up to snuff ...

 

[KennyPete]

Pulling the flywheel again is no issue, and I have been reading threads on 031 ignition issues for the past week. While I am new here, I'm no stranger to forums.

I have two of the electronic modules sitting here, which was actually why I pulled the flywheel in the first place (was going to set timing before installing it). I may try the WIMA capacitor since they're cheap. Just wish I could find one locally vs. ordering online.

 

[MnSam]

Here is a thread I did on one,

http://www.arboristsite.com/community/threads/reviving-031-spark.123190/

the pics are gone from the thread but I think I still have them. I'll look and send you a few pics in a pm. If you want to try the Wima route let me know, I think I have a few new ones laying around. I'll send one to ya.

 

[KennyPete]

Thanks! I read through your thread and I think that is the route I prefer to go.

Please PM me the pics from the thread, I would like to see how you mounted everything.

Again, thank you for being so helpful. I greatly appreciate it. I will gladly pay you for one of those capacitors if you have one laying around.

 

[TundraRider]

Following this. My uncles 031 is doing the same thing.

 

[KennyPete]

Success! She runs like new again!

Big THANK YOU to MnSam for his help. As per his recommendation, I replaced the condenser with a WIMA 600v .22uF capacitor. It was too tall to mount under the flywheel in it's original location, so I attached it to the tank with some epoxy. I grounded one side of the cap to a case screw on the inside of the tank, and ran a new wire from the points to the other side of the cap. I also ran a new wire for the kill switch at the same time.

I personally think this is beneficial over using a Nova/Atom/Omega module, and it's cheaper too.

 

[TundraRider]

Success! She runs like new again!

Big THANK YOU to MnSam for his help. As per his recommendation, I replaced the condenser with a WIMA 600v .22uF capacitor. It was too tall to mount under the flywheel in it's original location, so I attached it to the tank with some epoxy. I grounded one side of the cap to a case screw on the inside of the tank, and ran a new wire from the points to the other side of the cap. I also ran a new wire for the kill switch at the same time.

I personally think this is beneficial over using a Nova/Atom/Omega module, and it's cheaper too.

Did you get any pics to post of how you mounted everything?

 

[MnSam]

Did you get any pics to post of how you mounted everything?

If you are interested in this repair let me know, I'll send you a free Wilma.

And if Ken could post some pics of his repair that would be great. I'll put mine on here later this afternoon.

 

[TundraRider]

If you are interested in this repair let me know, I'll send you a free Wilma.

And if Ken could post some pics of his repair that would be great. I'll put mine on here later this afternoon.

I am intrested. I just went and dug mine and my dads 031s out of the shed to bring them back to life.

 

[KennyPete]

Unfortunately I didn't think to take pics as I went. If I ever have to fix another one I will take pics.

It is straight forward though. Here are the steps I followed

1.) Disassemble the saw - There are 5 screws on the gas tank/pull start housing, and you need to take off the 2 screws holding the handle on the bottom. Then there are two hidden screws on the clutch side - one in the air box, and one on the bottom to the left of the clutch.

2.) Remove the flywheel

3.) Disconnect & remove the old condenser.

4.) Run a new wire from the points to the new capacitor. I used 14 gauge and ran it along the same path as the kill switch.

5.) Since the flywheel is off, take the opportunity to clean the points.

5.) Reinstall the flywheel, adjust points if necessary - should be .016

6.) Solder wire to the capacitor before mounting it. Seal your connections heat shrink - I recommend using adhesive heat shrink because of the environment it is in.

7.) Mount the WIMA capacitor to the gas tank. I mounted mine on the left side behind the ignition coil using a little 2 part epoxy.

8.) Ground one side of the capacitor to the case screw on the gas tank. If you mount yours where I mounted mine, there is a screw about 1" away from it.

9.) Line up the halves of the saw, trim the wires to length, and solder them in the middle. Originally I was going to put a disconnect on here in case I need to replace it in the future, but due to space concerns I just soldered it.

10.) Reassemble it and try it out. Mine had great spark and even starts easily with a slow pull.

I hope this helps, and I apologize for not taking pics.

 

[TundraRider]

Unfortunately I didn't think to take pics as I went. If I ever have to fix another one I will take pics.

It is straight forward though. Here are the steps I followed

1.) Disassemble the saw - There are 5 screws on the gas tank/pull start housing, and you need to take off the 2 screws holding the handle on the bottom. Then there are two hidden screws on the clutch side - one in the air box, and one on the bottom to the left of the clutch.

2.) Remove the flywheel

3.) Disconnect & remove the old condenser.

4.) Run a new wire from the points to the new capacitor. I used 14 gauge and ran it along the same path as the kill switch.

5.) Since the flywheel is off, take the opportunity to clean the points.

5.) Reinstall the flywheel, adjust points if necessary - should be .016

6.) Solder wire to the capacitor before mounting it. Seal your connections heat shrink - I recommend using adhesive heat shrink because of the environment it is in.

7.) Mount the WIMA capacitor to the gas tank. I mounted mine on the left side behind the ignition coil using a little 2 part epoxy.

8.) Ground one side of the capacitor to the case screw on the gas tank. If you mount yours where I mounted mine, there is a screw about 1" away from it.

9.) Line up the halves of the saw, trim the wires to length, and solder them in the middle. Originally I was going to put a disconnect on here in case I need to replace it in the future, but due to space concerns I just soldered it.

10.) Reassemble it and try it out. Mine had great spark and even starts easily with a slow pull.

I hope this helps, and I apologize for not taking pics.

Thanks, I will have to get going on mine as soon as I have time.