Ms 200t spark problem

[Mark01987]

 

Having trouble with an ms 200t. Will run for a while and then just not start up. Have narrowed it down to a spark problem. Changed the plug so that’s all good but think it’s a problem with the wire leading to the spark plug. I have cleaned up the connection at the spark plug end of the wire several times and put it back together, the saw will then run great for a while but then the same problem will start again. I think it must be a loose connection. Is frustrating because I think I’ve solved it but it all starts again! Has anyone had trouble with this before? Any tips for a longer lasting fix?

 

Thanks!

 

 

[Ratman]

Could be the coil thats acting up when warm, you not got a known good one to borrow off another saw just to try it? If it is the coil then i would replace with a genuine one and not a chinese copy, they are pants and dont stand the test of time.

[ChrisNewport]

Coil is kaput or compression is poor and when you've been looking at the coil the engine has cooled enough to be able to start again.

[Wonky]

I,m going to say,, have you checked the spark plug, and that is, have used the plug from another saw, that runs well and stops when hot and starts again..

 

ive seen it once or twice, that two plugs behaved the same...

or test the plug in another saw. See if it does the same..

 

maybe disconnect the earth to the coil, to be sure it’s not getting a change in resistance enough to Earth it out. It's easy to stop a saw with no earth wire, you just choke. And also clean where the earth connects to the coil with carb/break cleaner

 

other than above you did not say if you have a spark when the saw has run and is hot and will not start.. ?
I’d swap the coil if I could borrow one to be sure..it was the coil..

coils do go bad, but there could be another good reason why it behaves like it is..

 

I look fwd to the fixed results ??

Edited April 3, 2020 by Wonky

[spudulike]

I have only ever changed one MS200T coils for going faulty and that was DEAD.

Two of the most common faults are: -

1) The black kill wire coming from the coil is earthing out and this can happen where it bends off the spade connector and disappears under the coil - it touches the metal case just above the bottom AV mount. The wire can also get pinched under the coil location pillars and generally happens when the coil has been removed. I did have one where the owner fitted an extra long top front AV screw which rubbed through the wire outer and earthed out when the AV was compressed. I agree with Wonky on trying to disconnect the black wire from the coil......surprised he didn't mention old fuel but there you go

2) The HT lead can play up, typically where it is clamped by the oil pump or within the HT plug cap when the spur comes off the lead. One Heath Robinson check is to get an old plug and bend the end electrode out or remove it and see if the spark will jump the gap, if it does, it is less likely the coil and HT lead are faulty plus any sparking from the HT lead will be visible in subdued light.

Other than that, the gap between coil and flywheel should be set with a plastic setting card or use a typical business card, if it is too large a gap, it can play up.

The other is that many miss the spark when tested and believe that the spark isn't there when it is in fact, working as it should - an old plug with the end electrode bent out at 45 degrees makes a good tester.

These coils tend to be pretty reliable and rarely fail. If the gap has been set far too tight and the coil has clouted the flywheel for a long period, it is possible to lose the magnets on the coil but have only seen this once on a MS461, never on this model.