MS661 -- No Spark

[Captain Bruce]

Who’s going to take back a module that you used for test? Just curious.
You can do whatever you like. A bad connection can give a spark for one revolution and no more.
Chances are you going to miss it without an in-line tester. But have at it.
Removing the carb is not a major undertaking. Not at all.

Anyone who offers free 30-day returns. ebay, amazon.....and used for test? Thats info. the seller would not have.....so the answer is, everybody.
A bad connection, referring to which connection? Am I missing something behind, replace wiring, and coil?
in-line tester? whats that? I'm using the clip on to the ground, plug into the boot, and pull in-line tester? Is there some new ghee whiz unit?
I have no issues removing the carb.; I was referencing my hope that a ignition coil replacement, which is a basic exercise, would be less time consuming than pulling the entire air filter assembly, linkage, carb.solenoid/micro-switch, and all that wiring....I certainly will be to that at some point. Just starting out with........"Has anyone found a solution to this problem.....""

 

[Captain Bruce]

Anyone who offers free 30-day returns. ebay, amazon.....and used for test? Thats info. the seller would not have.....so the answer is, everybody.
A bad connection, referring to which connection? Am I missing something behind, replace wiring, and coil?
in-line tester? whats that? I'm using the clip on to the ground, plug into the boot, and pull in-line tester? Is there some new ghee whiz unit?
I have no issues removing the carb.; I was referencing my hope that a ignition coil replacement, which is a basic exercise, would be less time consuming than pulling the entire air filter assembly, linkage, carb.solenoid/micro-switch, and all that wiring....I certainly will be to that at some point. Just starting out with........"Has anyone found a solution to this problem.....""

How does one achieve guru status, on this forum. Resume work?

 

[Jacob J.]

@Jacob J. could you help this guy? He seems like me. Pretty good on mechanical but the flow of electrons is somewhat of a mystery.

I don't have enough experience with these Mike to really offer anything. I recently rebuilt a low-hour smashed saw that was running both before and after. I got lucky - all of the ignition components were matched
and I didn't have to mess with them.

 

[rupedoggy]

Thanks JJ

 

[Captain Bruce]

I don't have enough experience with these Mike to really offer anything. I recently rebuilt a low-hour smashed saw that was running both before and after. I got lucky - all of the ignition components were matched
and I didn't have to mess with them.

Thanks for your honest reply.....and sincere admission that M-tronic has everybody scratching their ass......including another expert. I will figure this out and become a gura......................

 

[Jacob J.]

Thanks for your honest reply.....and sincere admission that M-tronic has everybody scratching their ass......including another expert. I will figure this out and become a gura......................

I'm foolish enough to know what I know, and yet wise enough to know what I don't know.

 

[DND 9000]

It is flooding/blow fuel out the carb.......as I try to start test for spark with a tester.....so I again presume the solenoid and miroswitch are functioning

How old is your saw ? Also please tell the year of manufacture and the serial number. It may also be possible that your solenoid valve is leaking. I think you have the black valve and a white pickup body in the tank.

 

[smokey7]

I wonder if you removing the yellow coating ruined the flywheel somehow?

 

[PogoInTheWoods]

So, now I find my need to add, that I am a 30 Yr. licensed, small engine mechanic.

First chainsaw, huh?

How does one achieve guru status, on this forum?

Usually by starting out with a little more humility.

 

[Captain Bruce]

I wonder if you removing the yellow coating ruined the flywheel somehow?

No chance. If anything, it makes for a stronger magnetic field. Its put on the face of the magnets during production, to ward off corrosion.

 

[Captain Bruce]

First chainsaw, huh?

Usually by starting out with a little more humility.

First M-tronic. Not sure what the other comment infers.......

 

[Captain Bruce]

How old is your saw ? Also please tell the year of manufacture and the serial number. It may also be possible that your solenoid valve is leaking. I think you have the black valve and a white pickup body in the tank.

Thats interesting. So, the solenoid on the side of the carb, is black. I haven't seen any that aren't....in my research on eBay. As to the fuel pick-up/filter, how could its plastic color influence spark? DOM = 7/13. How old is my saw? Its not my saw. No idea when it was purchased. owner has used it for 2 yrs. So, you suggest that the ignition coil is not making spark, given the signal being sent by the plug on the solenoid? Heres a question. What can be disconnected, so that the coil makes spark, outside of the wiring system? Seems to me, if something is grounding the coil.....and its unplugged, the coil would make spark? Serial #? What are the bad serial numbers?

 

[Tom82]

Thats interesting. So, the solenoid on the side of the carb, is black. I haven't seen any that aren't....in my research on eBay. As to the fuel pick-up/filter, how could its plastic color influence spark? DOM = 7/13. How old is my saw? Its not my saw. No idea when it was purchased. owner has used it for 2 yrs. So, you suggest that the ignition coil is not making spark, given the signal being sent by the plug on the solenoid? Heres a question. What can be disconnected, so that the coil makes spark, outside of the wiring system? Seems to me, if something is grounding the coil.....and its unplugged, the coil would make spark? Serial #? What are the bad serial numbers?

Mtronic saws aren't that complicated. Buy a new coil and fuel solenoid and be done with it.

 

[Captain Bruce]

Mtronic saws aren't that complicated. Buy a new coil and fuel solenoid and be done with it.

Being a fellow Canadian, I am working in that direction......hoped for a simple answer, but there are no simple answers, apparently?

eBay found a wiring harness, and coil. The fuel solenoid is functioning........if its purpose is to pump/supply fuel to the engine...its functioning. Thanks for your gentle shove.

 

[Tom82]

Being a fellow Canadian, I am working in that direction......hoped for a simple answer, but there are no simple answers, apparently?

eBay found a wiring harness, and coil. The fuel solenoid is functioning........if its purpose is to pump/supply fuel to the engine...its functioning. Thanks for your gentle shove.

The solenoid doesn't pump, its a valve that opens and closes as needed electronically.

The early solenoid valves are prone to run issues related to fuel not spark. When looking for spark, the coil is just like any other coil. The reason some asked about build date or what coil you have is because the early coils (even if running now) can be problematic in future and should probably be replaced. Same with the solenoid but, the newest version of solenoid will not work with older coils. So, it's best to just replace both with the latest updated parts. Stihl released a repair kit for the 661 that is a coil, solenoid, and fuel filter all of which are the latest and greatest. The kit should be under $200 Canadian. I've built or repaired several 661's, good saws once you get the bugs worked out.

 

[DND 9000]

What can be disconnected, so that the coil makes spark, outside of the wiring system?

You can`t disconnect the plug with the short circuit wire and the wire for the m-tronic. If you do this the control unit will not give a spark. Best would be to bring the saw to your dealer for proper diagnosis and repair, before you buy parts for nearly 200$.

 

[PogoInTheWoods]

Remove the plug wire from its routing channel and inspect the insulation for rub-through at both of the hard bends. Depending on how long the saw was operated with bad a/v, you may find exposed areas at those locations shorting out the ignition. Hell, I've seen it happen on 661's with perfectly good a/v. Have one with that exact problem coming in later today.

Again, carefully inspect the little wiring harness for possible pinches or breaks. There's a routine you can go through that will test the harness end-to-end along with the micro switch, though if you can hear the micro switch actuating, it's working. Wrestling the saw around to change the a/v components could have damaged the harness.

And fwiw, the reason questions are being asked about the color of your solenoid and fuel filter, serial number, etc., is to help determine which version of M-tronic this particular MS661C-M may have. They are all variables that have changed over time along with being mixed and matched trying to trouble shoot M-tronic problems. Not that it will help much aside from determining the probable version of M-tronic firmware and if it would indeed benefit from an upgrade to the latest v3.0 version which uses a white solenoid, orange fuel filter and particular ECM firmware.

Also fwiw, most dealers are going to tell you it's either the solenoid, the ECM, the carb, any combination, or all three -- and you already know that. Most are not up to speed on the M-tronic diagnostic system designed to further investigate such problems, let alone able to definitively tell you which component is actually bad..., if any even are. The book even tells you to replace what may be a perfectly good coil under a no spark condition. The dealer will, too.

Most folks would check the plug and plug wire first.

 

[Captain Bruce]

The solenoid doesn't pump, its a valve that opens and closes as needed electronically.

The early solenoid valves are prone to run issues related to fuel not spark. When looking for spark, the coil is just like any other coil. The reason some asked about build date or what coil you have is because the early coils (even if running now) can be problematic in future and should probably be replaced. Same with the solenoid but, the newest version of solenoid will not work with older coils. So, it's best to just replace both with the latest updated parts. Stihl released a repair kit for the 661 that is a coil, solenoid, and fuel filter all of which are the latest and greatest. The kit should be under $200 Canadian. I've built or repaired several 661's, good saws once you get the bugs worked out.

Thanks Tom. pump/supply. I used the words loosely. Wonder why a device would close as needed? other than when the shut-off is grounded.....and the saw stopped?
Anyway, how do I find this kit you reference? 200 Can, is about 130 US.....and coils run that much by themselves.
DOM is as mentioned = July 13. The coil is marked 1144 4700 C. Also, as already mentioned, with the spark tester connected, and no plug in the block, while pulling to test for spark, plenty of fuel is being introduced; hence my assumption that its electrical.

Anyone with a part # for the retro-fit kit, please chime in. Tom82, thank you for your continued involvement.

 

[Tom82]

Thanks Tom. pump/supply. I used the words loosely. Wonder why a device would close as needed? other than when the shut-off is grounded.....and the saw stopped?
Anyway, how do I find this kit you reference? 200 Can, is about 130 US.....and coils run that much by themselves.
DOM is as mentioned = July 13. The coil is marked 1144 4700 C. Also, as already mentioned, with the spark tester connected, and no plug in the block, while pulling to test for spark, plenty of fuel is being introduced; hence my assumption that its electrical.

Anyone with a part # for the retro-fit kit, please chime in. Tom82, thank you for your continued involvement.

I will get you the part number for the repair kit at some point today.

 

[Captain Bruce]

Remove the plug wire from its routing channel and inspect the insulation for rub-through at both of the hard bends. Depending on how long the saw was operated with bad a/v, you may find exposed areas at those locations shorting out the ignition. Hell, I've seen it happen on 661's with perfectly good a/v. Have one with that exact problem coming in later today.

Again, carefully inspect the little wiring harness for possible pinches or breaks. There's a routine you can go through that will test the harness end-to-end along with the micro switch, though if you can hear the micro switch actuating, it's working. Wrestling the saw around to change the a/v components could have damaged the harness.

And fwiw, the reason questions are being asked about the color of your solenoid and fuel filter, serial number, etc., is to help determine which version of M-tronic this particular MS661C-M may have. They are all variables that have changed over time along with being mixed and matched trying to trouble shoot M-tronic problems. Not that it will help much aside from determining the probable version of M-tronic firmware and if it would indeed benefit from an upgrade to the latest v3.0 version which uses a white solenoid, orange fuel filter and particular ECM firmware.

Also fwiw, most dealers are going to tell you it's either the solenoid, the ECM, the carb, any combination, or all three -- and you already know that. Most are not up to speed on the M-tronic diagnostic system designed to further investigate such problems, let alone able to definitively tell you which component is actually bad..., if any even are. The book even tells you to replace what may be a perfectly good coil under a no spark condition. The dealer will, too.

Most folks would check the plug and plug wire first.

Now, we are getting somewhere. The lead to the plug boot, shows some minor scuffing......albiet it is running thru a plastic channel. I tested that lead from end to end, and it showed zero breakage/ zero resistance. The coil # = 1144 4700 C. The solenoid is black. I have both black and orange fuel filters.........
As to dealer service......thats a slippery slope in this area. The major Stihl dealer insists that the unit, any unit, must be brought to the store. That includes walking in with the part # for an air filter, for a 290.....very uncooperative service dept. I inquired as to the diagnostic charge, for checking the system on this 661, with the MDG-1. I was told it is not a possible service. "We won't plug in and test, and tell the customer what the data says....." Odd.

Any part# for the up-grade would be greatly appreciated. My crossed - fingers are now open to suggestions. Replacing the coil is the first, and fastest step to spark. I will remove and VOM test the wiring for resistance first. Thanks for your insight. Now, I know frustration is easily abated, with a few simple questions, and some humility.