No Spark on a Briggs

[94BULLITT]

Someone I know has an old homelite generator with an 8hp briggs on it. He checked it and it did not have spark. He got a new briggs coil for it and still could not get it to run. So he brought it to me. I checked the coil is on the right way. The air gap was off a tad so I corrected it. Still no spark. Finally I got smart and used a drill to turn the crankshaft, and it had spark. I checked it with my tach and it looses spark at 147RPM. I've tried messing with air gap to get spark at a lower RPM and it does not help. Usually you can have the magnet at the coil, and work the flywheel up and back and you should see spark. You can't with this. The old coil does the same thing. The magnet on the flywheel is super strong. My question is, at what RPM should it make spark? Any ideas at what could be going on? It does not have points, it has a solid state ignition.

 

[Steve]

What brand sparkplug are you using?

 

[94BULLITT]

Champion is what the guy sold him with the coil. I also tried a new NGK that I keep for saws.

 

[Steve]

I have had issues with the electronic coils not producing enough Kv while cranking. Would not spark an ngk. Using a champion plug got me spark.

Is this a flat head 8 hp?

Using an RJ19LM?

Try a J19LM without the reistor.

 

[Steve]

Also im sure you tried to get spark without the kill wire hooked up? I have had one that had a bunch of oil and crap built up around the kill switch half grounding it. That one kicked my azz!

 

[e.fisher26]

Weak magnets


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[94BULLITT]

Yes flathead. I'm guessing it was made in the 80's. The engine is red. I think it is a RJ19LM. I'll see if I can find a plug without a resistor.

 

[e.fisher26]

Walmart has them, it’s just J19LM


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[94BULLITT]

Also im sure you tried to get spark without the kill wire hooked up? I have had one that had a bunch of oil and crap built up around the kill switch half grounding it. That one kicked my azz!

Yes, I've checked it with the kill switch disconnected, and the low oil *s-word down.

Weak magnets


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I don't know, if the coil touches the flywheel, it is pretty hard to pull off. Is there a way to check the magnet?

 

[94BULLITT]

Walmart has them, it’s just J19LM


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I may have a non resistor plug laying around to test it.

 

[94BULLITT]

I remembered that I had also tested it for spark with out a plug, and I also used a spark tester, the kind that you can adjust how much the spark has to jump. It did not have spark then, so it is probably not the plug.

 

[Steve]

Then it must be the flywheel. There is nothing else.

Just for giggles did you ground the spark tester to the coil lamination or the cylinder head?

 

[Wonkydonkey]

There is a way to test a coil with a multi meter.. google is your friend..
I had a coil go bad on a Briggs, however someone swapped the pull start casing and the numbers did not work in our favour.. the piece of junk is still sitting there

 

[Wonkydonkey]

Sorry if you seen this before.. of you have already gone over these steps,,, but some times we need to be sure we’ve checked everything right
https://www.briggsandstratton.com/e...rowse/ignition-system-theory-and-testing.html

Or this may help..

 

[94BULLITT]

Then it must be the flywheel. There is nothing else.

Just for giggles did you ground the spark tester to the coil lamination or the cylinder head?

It was grounded to a head bolt.

How do I check the flywheel? All I have seen a 12" straight screwdriver should stick to it. That is pretty vague because the weight of screwdrivers can vary.

 

[94BULLITT]

Sorry if you seen this before.. of you have already gone over these steps,,, but some times we need to be sure we’ve checked everything right
https://www.briggsandstratton.com/e...rowse/ignition-system-theory-and-testing.html

Or this may help..

I skimmed the Briggs link. It was similar to what I had found somewhere elsewhere, saying check the spark at 300RPM. I have spark at 147RPM, when turned by a drill. I can't turn it that fast by hand.

I'll check out the video later and look at the Briggs link.

 

[Al Smith]

Some times although rarely the ground connection where the coil mounts to the engine block the aluminum will get tarnished creating a high resistance to ground path on the low voltage side of the magneto . sand these connection points and the coil .it might make a difference .

 

[AVB]

Since you have spark at 147 rpm which is below the minimum rpm spec, have you checked the valve clearances? On this older of engine the gap is probably nearly closed up. Once nearly closed no matter how good of a spark you have the engine will not run due to over active decompressor.

 

[stretch5881]

I have already replaced coils with new and had the same issue. I went through all the same BS of testing everything and everything tested the way it should. As a last effort, I changed the coil again and all was good.
I have been repairing engines for 40 years. Buying replacement electrical parts, I had found, just because it's new, doesn't mean it's not faulty right from the factory.

 

[94BULLITT]

I had cleaned were the coil mounts to the engine which it was not dirty to begin with. I told the guy to get another coil. The shop where he got the coil told him to bring the whole generator in. The told him a plastic piece was missing on the switch and charged him $40. The funny thing is, I tried starting it without the ground wire hooked to the coil and did not have spark.

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