OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Echo Brushcutter

Have a really old Echo brushcutter Model SRM 302B DX.
It gave remarkable service until one day it would not start. Have worked out it has no spark. Tested the coil as per the video I found on this site which tells me the coil is faulty (I think).

Would anyone have any ignition bits for this machine? Or advice if you think there are any other things I should check?

If there is no spark, there seems to be no point in looking for other faults until you fix that one. Are you sure you had isolated the kill wire when you tested the ignition system? Faults with brushcutters and chainsaws are usually in the fuel system rather than the ignition system, except where there is a problem in the kill circuit (on/off switch wiring). Failure of the tinpot switches they often use is reasonably common.

You did test the ignition by trying to make a spark from the high tension wire to earth, not across the spark plug, didn't you? Spark plugs don't last long in 2 stroke engines, so you never consider you have an ignition fault unless you can't get a spark from the HT wire itself.

No. I did test it via the spark plug, but tried it with several different plugs just to make sure.Will try again without a plug.

The coil has a black and a red wire. The black goes to the kill switch and the red via conduit to a dark grey moulded plastic "thing" from which the High Tension lead comes. Not sure what that object is called. What gap should there be between the coil and the magnets on the flywheel?

Breakerless ignition systems are either one piece or two piece, depending on whether the switching system is integrated with the coil or separate from it. The piece that the HT lead comes out of, is always the coil. If there is a second piece, the wire that connects the two is likely to be the switching wire to the coil primary, that triggers the ignition.

The gap between the flywheel and the laminated steel part of the magneto is just about always 0.10 to 0.12". A standard visiting card is about 0.12", and is a convenient gauge for most people, because it is both bendable, and non-magnetic.

Tried without a plug and still no spark.
It seems I was confusing the magneto and the coil. Now I understand which is which.

Will check all wires for continuity and insulation breakdown.

If that fails to produce a result will still be on the lookout for parts. Local agent not interested -too old, only wants to sell me a new one.

A minor point, Tinsel: the entire system is the magneto, whether it is an integrated unit like Briggs' Magnetron, an electronic module and separate coil, or a set of breaker points and separate coil.

It is usually worthwhile to disconnect the kill wire, to make sure you are not being fooled by a defective switch on the end of the wire.

There are no points,just the magneto on one side of the flywheel and the coil on the other side.I have definately disconnected the kill switch.

Jim

If the kill switch is isolated, the flywheel gap is correct, and none of the wires is grounded, it sounds as if either the module or the coil is defective. If you have a multimeter you could check the resistance of each side of the coil - primary to earth, and secondary to earth. The primary is connected to the wire coming from the module, and the secondary is connected to the HT lead.

Hey Grumpy,
You strike me as a man of both extensive knowledge and experience (each no doubt has been a result of the other). I expect you have also experienced the phenomenen as I have, of fixing things by just "having a look at them"!!!!
You pull them apart to find a fault, cant find anything, put it back together and away it goes!!!!

After your last helpful post I checked the magneto gap with a card, tested the resistance over the primary and HT wires and put it all back together. BINGO I now have spark. I did not alter anything, just looked at it!!!

Is this a variation on "Sods Law"??

Sadly I think it means there is a cracked or broken wire which I have disturbed to make connection again and in due course it will let me down again.

Will put it all back together tomorrow and report back. In the meantime your comments on my experience would be greatly valued.

Jim

I agree with you Jim, things that fix themselves when you dismantle and reassemble them have a problem that will probably come back. In this case it is very likely to be a bad ground connection or chafed-through insulation on a wire somewhere. How does the coil's ground look? It is fairly common to have a problem with that because the coil is mostly made from steel and it forms a voltaic cell where it clamps to the aluminium engine. The aluminium oxidises and forms an electrical insulator. Cleaning both the aluminium and steel parts then reassembling them, fixes that particular fault for years.

All back together and with a couple of doses of fuel down the plug hole away she went.

Thanks Grumpy for your advice and encouragement. Now to work out why the cheap Chinese one I bought to replace it will not run for more than a couple of minutes.

Love this site.

Jim

Glad it's working, Jim. I'll close this thread - just open a new one next time you want to discuss a problem.