MS661-What are the chances...

[mopar38]

Employee backed over my MS661... thankfully was repairable. Needed new handle, handle mount, fuel cap and a couple screws...not too bad. Put saw back together, fired right up. Ran for 45 sec. and shut off. Wouldn't start... checked for spark, none! Disassembled and checked switch, plug, coil and wiring. Put back together... nothing. pulled fast... got small spark... very intermittent. Was able to get saw to start but would not stay running. I think the coil/control unit bad. Thinking it's coincidence but is it possible getting run over could have done something even tho coil and wire weren't visibly affected or damaged? Also, if I replace coil with new will the calibration process be different than it was with the original?
Thanks... any input appreciated.... including suggesting I get a new hired man!

 

[CentaurG2]

Oh man, that guy is an amateur. I would have backed over it twice to make sure it was good n dead.

 

[DND 9000]

That depends on which control unit you get. If you get the older 1144 400 4720 (on coil 1144 4701 A) the calibration process is the old one. If you get the newer control unit 1144 400 4703 or 1144 400 4704 (on coil 1144 4702 A) with firmware v3 the calibration is different.

New calibration, best to do in conjunction with the diagnostic tool. But can also be done without it. Start the saw on cold start and let it run at least 30-60 sec without touching the throttle trigger. After that give full throttle and hold it for at least 30 sec. Rpm`s climb up until they reach max. If max is reached they drop back to around 10.000 rpm. Release the throttle trigger and shut of the machine. Done.

 

[Canyon Angler]

After that give full throttle and hold it for at least 30 sec.

Running a barely warm motor at WOT under no load for 30 sec would give me the heebie jeebies, so I guess it's good I don't have a 661!

 

[Wood Doctor]

That employee cost you about $1,300. Get a new saw. You could be messing with that run-over saw forever. You might get $100 for parts on our Tradin' Post. Or, you can keep this beat up jewel for your own parts and future repairs of other saws.

I hate to see these things happen and I am sorry for your loss. I am sure your employee is sorry also. **** happens.

 

[DND 9000]

Running a barely warm motor at WOT under no load for 30 sec would give me the heebie jeebies, so I guess it's good I don't have a 661!

I know it sounds scary, but it`s like that.

 

[mopar38]

Still dealing with intermittent spark with new coil/control unit. Didn't even get to the calibration yet! I did read that with a lower than version3 you can speed up auto-adaptaion to optimum power by five full throttle cuts to length. Do you also need to run calibration as well on the version 2? (1144 400 4720) Kinda perturbed, local dealer doesn't have computer to check my intermittent spark issue. Checked over all points according to work shop manual and always end up at coil issue. Anyone else have no spark issue that was not related to coil?
BTW thanks to all who replied, your opinions are appreciated!

.....Latest finding... have spark without compression. No spark when spark plug installed. This is with new coil/control unit installed.

 

[DND 9000]

Yes you have to go through the calibration if you change the control unit, carburetor or solenoid valve, especially when the electrical connections are unplugged. Start the saw on the cold start mode and let it run at least 60sec. Move the master control lever all the way to stop after the 60sec withouit touching the throttle trigger. After that you can start in normal run (I) mode and make the 5 cuts for the self tuning to the current conditions. After that the saw should be fine.

With you spark issue: Did you check the gap between the control unit and the flywheel? Should be 0,3mm. Also check the electrode gap on the spark plug (0,5mm). What`s with all the wires, no short circuit or bad isolation? Could also be a reason for a bad spark.

 

[mopar38]

Yep. checked all wiring, reset gap at flywheel when installing the new one. After tearing down and reinstalling flywheel, control unit, checking all wiring and contact points saw starts 1st pull but will not idle. Can not do calibration as indicated because the first step is start and idle saw for 60 sec. without touching throttle.
If you allow saw to shut off, it does not have spark and you cannot restart. If you allow the thing to sit for approx.15 min., will fire right up, but again will not idle. After waiting 15 min. for the third or fourth time said the hell with it, and started it , ran it full throttle through 5 full length cuts. Could hear saw adjusting itself throughout. When finished cutting, saw immediately shut off when it idled down. Would not restart- no spark again. I'm about ready to run it over it myself!!!!... 10x!
If I can't get this thing figured out, am seriously considering converting it to a non-mtronic set-up. Don't want to give up on it, this thing is a beast when it's running. Any good hard numbers out there for converting?
Thanks for the input.

 

[DND 9000]

I`ve read somewhere or on the other side O P E that if the electrical connection to the solenoid is malfunctioning, the control unit shuts down the ignition. A other guy (Stihl mechanic) said that there is spark for a short time. With that you know the control unit works. Switching off the ignition is to prevent the engine from flooding, because if there is no electrical connection to the solenoid it is always open and the engine would flood.

Could it be that the saw is running to rich because of no calibration? In the past I changed a control unit on an MS 241 and I needed 5 or 6 times to calibrate the control unit, because it ran way to rich, flooded several times and smoked heavily. But suddenly it cleared up while calibrating and worked. Maybe you have to try it again?

 

[mopar38]

Have checked wiring and connection at solenoid (okay). Maybe solenoid bad? Don't want to go that route... more $$$ to replace, if that's not gonna make the saw right. Is there a way to check the solenoid itself without putting it on the computer diagnostics?
Thanks.

 

[DND 9000]

It can be tested electrically with an ohm meter. Range should be between 28-42 ohms. If you are in that range, the valve is electrically ok. That dosen`t mean that the fuel flow function is right. That can only be checked with a pressure pump. (if it is tight) The dealer can do that. Go to one that is proprely equipped and trained.

 

[mopar38]

Thanks, will do that. If there is not an issue with the solenoid I'm giving up, everything thing else checks out okay. This electronic stuff really puts a hurtin' on an old school Stihl mechanic, can't compete with a computer...they'll take you out every time!