Ms500i no spark

[idiotwithasaw]

I picked up a 500i from a local dealer out of his parts pile, saw looked good but was in pieces. I asked the owner why it was parted out and the answer I got was "i dont know", he has multiple mechanics so I wasn't surprised. Either way I got it home and started inventorying what all was missing. Wasn't too bad and didn't take long to find some parts and I slapped it together tonight.

As I was going through it I checked for spark First with the plug laying on cylinder method and then with a spark tester and no dice. I tried it with thekill switch plugged in and without, I've never worked on one of these before where should I start.

 

[ZeroJunk]

You have a generator under the flywheel. A control cable that goes to the "computer" and a "computer" .

Make sure a lead of the cable has not shorted to the magnesium. You can do that with an ohm meter. Or magnifying glass maybe.

I'm assuming they hooked it up to the diagnostic system and got no answers.
Even the computer is only like $250, so worth replacing on that saw. Doubt is the generator, but who knows.

Sort of a labor of love on those things. They may have just not wanted to screw with it. Or, more than just no fire wrong.

 

[idiotwithasaw]

I haven't pulled mine but would a sheared flywheel key cause this on the 500i

 

[ZeroJunk]

I don't know how they time it. Would be curious to know. Has to be a position sensor somewhere.

But, if the flywheel is not turning in the stator then it certainly won't have any voltage.

Well, that doesn't really make any sense because you would feel that instantly because you wouldn't be turning the shaft.
If it is just not timed right it would still be firing some time.
Maybe somebody will chime in who knows

 

[hacskaroly]

As I was going through it I checked for spark First with the plug laying on cylinder method and then with a spark tester

A couple of quick things to check and eliminate:
1. Try a known good or new spark plug, if still no spark, then it not the plug.
2. Inspect the spark plug boot and the torsion spring inside. Many times pulling on the boot a little too hard pulls out the torsion spring and can even break the point off that is shoved into the wire leading to the coil. It is possible a tech broke it and shoved it back on and walked away. If it is intact, make sure the torsion spring is touching the center conductor on the wire and is fit in the spark plug boot correctly. A multimeter can help determine continuity between the coil and the torsion spring.
3. If you had to reseat the coil, did you gap it correctly to the flywheel?

These are three quick checks to help eliminate everything past the coil as a potential issue.

 

[Chevboy0167]

https://www.ebay.com/itm/2252488227...1291&msclkid=5bcaa834c7fe1dedd873cd55c0c013c8
https://www.sawagain.com/stihl-ms-5...ign1&msclkid=4297637f69ac19efca3c061e6ede7757

 

[ZeroJunk]

I guess that answers that.
https://www.sawagain.com/stihl-ms-5...ign1&msclkid=4297637f69ac19efca3c061e6ede7757

 

[PV Hiker]

I thought I read someplace that a person had a faulty kill button preventing spark. Might be easy to look at?

 

[idiotwithasaw]

This was a pile of parts when I got it and honestly I have no experience with these saws. I went to an Amish run stihl dealer that works on these to get some spare parts. And yes I laugh at the idea of Amish working on 500is lol, but they say they swap parts on them all the time so they must be fairly simple to work on.

I haven't seen anything on it that looks like the ignition sensor that was posted on sawagain, but there is a blue port with a connector that looks like the one in the photo so I assume it's there.

As far as the kill switch being bad that could be a possibility, the one I have was obviously fiddled with and the orange plastic part was missing, do you know if it will fire with it unplugged?

 

[Woodslasher]

This was a pile of parts when I got it and honestly I have no experience with these saws. I went to an Amish run stihl dealer that works on these to get some spare parts. And yes I laugh at the idea of Amish working on 500is lol, but they say they swap parts on them all the time so they must be fairly simple to work on.

I haven't seen anything on it that looks like the ignition sensor that was posted on sawagain, but there is a blue port with a connector that looks like the one in the photo so I assume it's there.

As far as the kill switch being bad that could be a possibility, the one I have was obviously fiddled with and the orange plastic part was missing, do you know if it will fire with it unplugged?

500i's may be special, but on a standard saw you will get spark even if you disconnect them.

 

[idiotwithasaw]

Well I got it running. I checked the kill switch and it ohm'd out good I cleaned all the connectors with electrical cleaner and hooked it all up and it got spark. Not sure if that is what did it or I just wasn't pulling hard enuf. Somehow I managed to get it to pull fuel and she fired right up, I am extatic.

 

[idiotwithasaw]

Thanks all for the help.