# Stihl coil question (BR200 blower)



## telesis (Nov 10, 2016)

This is really directed to anyone who is an authorized STIHL tech or who has intimate knowledge of their products.

This is a 2 year old blower, low hours, has always started and run reliably. Customer was using it on Sunday and it just stopped running and won't restart. I've checked all the usual things(I have extensive small engine experience). Plenty of spark and fuel. Sure seems like timing. Can't get a single pop. Pulled the flywheel and the key looks somewhat iffy so I'm going to my local dealer where this was bought and compare with a new flywheel for giggles and grins. I'm also going to ask about the coil as I describe below.

In the meantime, I found one thread on the web on another site discussing the exact same problem(I checked here but didn't find any specific coil reference). Someone commented that Stihl has had coil problems that manifest themselves as timing being off, but not gone. IOW, the coil is still producing spark, but due to an internal malfunction, it's happening at the wrong time (suggesting an electronic component failure inside). The person also stated Stihl has a lifetime warranty on the coil.

So... can anyone confirm that you've experienced a similar failure mode? Can you confirm if there are known Stihl coil problems? Specifically, timing being off, but still there, due to a coil problem (not the flywheel at all)! Are you aware of a lifetime warranty on their coils?

Any insights appreciated. Thanks!


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## paulr44 (Oct 14, 2008)

No, it's extremely rare a STIHL coil timing module fails. When they do, the engine will usually idle and when attempted to rev up, they'll sometimes rev up fine, but a few seconds later on a retry it'll sit at idle and lug like it's getting too much fuel. So I doubt that's the issue.

I suggest you check the exhaust screen for being plugged up...that's often an issue.

And yes, I'm STIHL Silver qualified.


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## telesis (Nov 10, 2016)

Thanks Paul. I thought you and/or 30yr were Stihl certified. I spoke to the service manager at my local dealer where my customer purchased this. Unfortunately they didn't have the flywheel in stock so I couldn't compare the key area. Likewise, he was not able to confirm any lifetime warranty on the coil although he did see some specific verbiage related to ignition related components. He thought he had heard about the problem I mentioned but could not find any info about it in writing.

However there is a pot of gold at the end of the rainbow. The unit had a 2yr warranty which expired last year. My customer has had it 3 yrs, not 2. But the records show he purchased synthetic oil at the time of the purchase which automatically extended the warranty an additional 2 years expiring in 2017. So... it's covered. He said put it back together and bring it in under warranty!

FWIW, I did check "all the usual suspects" including exhaust(clean as a whistle), compression, spark, etc. I'll happily let them fix it under warranty as either the flywheel or coil or perhaps both. I'll follow up and share the results.


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## paulr44 (Oct 14, 2008)

I was going under the assumption you were more of a novice, sorry about that.
You don't need a new flywheel to compare yours, you can determine it's condition visually.
They don't list a flywheel key in the IPL, so that means it's built into the flywheel. Also, almost (but not always) when the built-in one shears, there's evidence of that on the crank (scratches or scoring around it) and or aluminum scraped off by the keyway.

I have seen them shear off at times, usually when someone is too ambitious with an impact gun on a chainsaw clutch - you have to go easy or use a piston block and hand tools. It's extremely rare for one to shear on it's own or from a backfire etc.

As with any engine, you can get a pretty good idea if the key is sheared badly by simply observing piston and flywheel on the compression stroke when turned over by hand - 2 stroke or 4 stroke. The magnets should pass under the coil at close to TDC, as they're often set to fire from 0.120" or less of piston achieving TDC. Or, think of it in crankshaft terms...8 or so degrees BTDC. Many Stihl products have a retard capability, so the coil is further advanced than that 8 degrees or so, and at idle it holds the charge in capacitors until the right moment, and lets it advance as RPM increases. This is good to know as the flywheel may appear to pass under the coil too soon on such an engine.


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## paulr44 (Oct 14, 2008)

P.S Stihl never had a lifetime coil warranty. Their warranty at one point did include an extended coil warranty (parts only) but that program was phased out a long time ago. Coils are covered under the EPA component warranty, which means regardless of the overall product warranty (be it 90 days such as a cut-off saw) or what have you, the OEM has to cover it for 2 yrs.


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## finaprint (Jan 29, 2006)

'The magnets should pass under the coil at close to TDC, as they're often set to fire from 0.120" or less of piston achieving TDC. Or, think of it in crankshaft terms...8 or so degrees BTDC.'

This. 

Any engine will run if that is on that close. Other than that, the only way timing could be off was if the coil winding resistances are off or weak or shorted solid state component but I have no idea if there are published specs on that. Used to cars and bikes and they all give that. Should be fine though if you are putting out strong spark, the resistances being faulty won't do that. A cap partially shorted to ground could cause issues.

If flywheel magnet to TDC timing is correct then any out of time would be from electronic issues and by virtue of that would have to be a weaker spark since the errant timing would be missing the highest point of magnetic flux from the flywheel. Max spark comes from that timing event lining up with the most magnetism.

Possible sudden vacuum leak from broken hose?

I've heard a few wild claims of magnet in flywheel suddenly going bad but I don't really buy it. 

Restarting efforts may have simply fouled the plug out to ignite down the porcelain of the plug. Plug can fire airgap clean at out and testing but fail under running pressure. Try a new plug. Try a small shot of ether, if that doesn't pop off any at all you have pretty much a solid problem there. Ether will light off a fouled motor most of the time.


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