Briggs 19G412-0129-01 Magneto problem?

[dart451]

Wondering if the magneto in this engine is bad. I've taken off the shroud/pull rope and have been spinning the flywheel with a drill. I don't seem to be getting much spark. I have disconnected all the grounds making sure it's not grounded, I put my inline ignition tester on, light won't flash when turning it over. ( I checked it on another known good engine, it flashes) When I ground myself out, while cranking the flywheel, I do feel some juice but normally, I'm used to getting knocked on my backside when I have good spark! lol So, I thought magnetos usually just go out without giving any juice...do they become too weak to work sometimes? Never had this happen before...

In case I didn't mention it...this engine is on a Generac generator 5000

[RoyM]

They do go bad, that engine is getting on in years

[KE4AVB]

With electronics involved just about anything is possible. I have seen things that I have been told was impossible to happen.

I would however check the strength of the magnets. I have heard of them losing the their strength though I have never seen it myself.

Dart you should be able to a donor coil for testing if you have few used engines sitting around for parts. The 398811 coil is used on 7hp to 16hp single cylinder engines, such as 170000, 190000, 280000, and 310000 series.

[38racing]

there was a point in the 28 series when briggs went from 398811 to the 492341 which has some advance built in I believe. It is noted by having a gap between the laminates at the end away from flywheel.

[KE4AVB]

I stand correct as not all models will have the same coil due newer engineered models but most older will have the coil I indicated.

[dart451]

Thanks guys! I didn't have a magneto to try so I just ordered one....hopefully, that will fix the problem. But, if the magnet is weak, I'm back to square one. Should get it today so I guess I'll see today! I actually spun the flywheel with my drill while grounding myself holding the plug wire with screw driver inserted. (My way of telling whether there is enough spark! lol) I could hold it through several revolutions...they usually knock me on my a!

[KE4AVB]

Try getting hit with 36Kv instead instead 12-15kv. It will teach you to respect the circuit even when it is off. And I had the tip of one finger with 3rd burn plus a hole in my forearm from 500vdc power supply even when it was off, it was a lot damage. The power supply builder didn't install safety bleeders. It had them when it left the shop.

[Arkie]

Yes about weird magneto issues, I've seen some magneto's that will test good on a ignition tester but NOT operate correctly when on the engine due to being slightly ??? and they would also produce a spark when tested on the engine.

I now use a Briggs 19368 spark gap tester ($11 with free shipping) instead of a in-light or the finger in spark plug hole method. (or if the magneto is not too expensive I just do a sub when I suspect such. I've never seen a weak flywheel magnet cause magneto ignition issues, but heard rumors of such.
I've had the inline type tester lights flash when the spark was too weak for the engine to run, therefore I do not trust them as good ignition testers.
You may have to locate the viewing window of the 19368 spark gap in a darken place or shade because sometimes a very hot white spark is not readily visible unless the viewing window is shaded.

The 19368 can also be installed in series with the spark plug to watch for intermittent loss of ignition as the engine is running.

and a electrical shock can ruin a good pair of underwear also.

[KE4AVB]

Not to mention that though a coil is firing with the plug in or out of the engine it still firing at the wrong time. Note: just because a spark plug will fire out of the engine doesn't mean it will under compression. Even had one that fired until starting under a load

I had several coils on chainsaws (2 cycle) that simply was firing at thee wrong time this alone.

Several years ago I had Kawasaki with the ignitor setup to shoot out one foot flame of the exhaust with a very load report when it misfired. The first time it did I was right in the exhaust path with my pants leg. Loss a lot of the hair on my lower leg. On top that it scared the heck out of me as was like someone pulled the trigger on my Comanche III or the 12 ga Mossberg right behind me. I think my heart might have skipped a beat or two at the time.