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WRAP UP Stihl BR 550 Blower Symptoms: When cold, blower starts on second pull every time, and runs great for a minute or two, then dies like either fuel or spark was shut down. Repeated attempts to restart are futile. Engine won't even attempt to turn over. Wait about 10 minutes and items 1&2...

Thanks for this. I suspect more is going on inside these coils. My research indicates that the coil is processor-based to provide automatic timing adjustments. However, I think you're spot-on regarding insulation breakdown as my basic problem.

Gentlemen, my blower is back! Short version: Today, my lovely wife ventured to the local Stihl dealer and acquired a new coil. After I got home from work I dropped it in, and it ran without looking back. In the dark I ran it though its paces on the leaves in the backyard without any hesitations...

Wolf, I'm a EE. Been using Fluke meters almost my entire life, and used one to make this measurement. You had it set up correctly. The only wild card is a defective meter. I had mine on an auto scale just like you, and they largely agree. The only exception is the wildly different coil tap to...

Wolf, that's a generous offer and I appreciate it. In fact, after my initial post on this forum I didn't expect any responses. What I got was a bunch of guys who are as invested in making this thing run as me. Been a great experience regardless of how it turns out. My plan is to make this final...

The new carb is not OEM, but it now acts that same way as the original. I contemplated a leak-down test weeks ago, but I don't have the fixtures and other equipment to do it. And I'm reasoning that if I have a leaky crankcase or rings, the thing is junk anyway. I can't fix that myself, and the...

Update. No replies necessary or expected. I went out this morning and bought myself a brand new NGK plug to begin today's festivities and to satisfy breese's observation. Installed it, and after two pulls the engine springs to life, runs for a minute or two, and then dies. Pull, pull, pull...

Made the measurement again...20.3 kΩ. Same as yesterday. The measurement is the same regardless of lead polarity, and I verified that my meter is accurate with a known 100 kΩ resistor. This is a BR550, but I've verified that it uses the same coil as your BR600. I think that given your...

Before I leave this completely, I assume that the red lead is connected to the red input of the meter and the black to the black? Sorry, but can't see from the pic.

Whoa. That kills that idea. I'm going to measure mine again tonight. Maybe I managed to screw up this simple measurement. If not, it's impossible to understand why two coils that should be identical yield such wildly different results. And for that matter, how mine is running at all. Thanks...

Plug has not been replaced. It's NGK and original to the blower. Thanks for the suggestion. I'll change it this weekend. Cheaper than a new coil at least.

Yes, some do to mitigate EMI. However, 2 MΩ is way too high for that application.

Red lead on the plug wire Black lead on the coil tap (not ground). In other words, just like the first pic that measured 2.302 MΩ, but reverse the leads. Thanks. I appreciate all this.

Wait. I think I have this. There are active components inside the coil pack. I suspect that if you reverse the leads on your ohmmeter you'll forward bias a junction and measure closer to mine. Can you try that?

Okay. That's interesting. That's between the coil tap and plug. I measured only 20 kΩ on mine -- over two orders of magnitude lower than yours. I know that that the BR 600 and BR 550 use the same coil. Makes me wonder how mine is working at all. Yours does run well, right?

Thanks. I appreciate the information. 0.2 mm is about as thin as paper, which is interesting. I'll double check, but I don't think the gap on my blower is that small. BTW, two PostIt notes stuck together is 0.203 mm. Perfect!

Never mind, I see one pic between the coil tap and plug wire. Is that reading 2.302 Ω, kΩ or MΩ. It's hard to see the meter.

Thanks. Your measurement is between the plug wire and ground. Mine were between the coil tap and the plug wire, and coil tap and ground. In other words, I was on the other spade connector.

Wow! Do you guys ever sleep? I really appreciate the fast a great responses to this problem. I guess, as the saying goes, in for a penny in for a pound, the best approach is to buy a new coil pack. They're fairly inexpensive and would either solve the problem or eliminate ignition from the...

I made two coil resistance measurements: Coil tap to plug wire: 20.27 kΩ Coil tap to ground: 18.18 kΩ I checked the strength of the spark. I can't say that the color was blue, but it was a bright white and arcing at least 0.25 in. I also checked continuity of the the kill switch at the coil...