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No spark to plug on 5HP small engine


Gunn's Avatar
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01-21-16, 04:52 PM   #1  
No spark to plug on 5HP small engine

I have a Briggs & Stratton Model 130212 Type 0970 5HP engine on a snow blower. This is around a 1979-1980 engine, so I think the ignition coil uses points. It worked great the last time it was used, which was a couple of years ago. I fully expected to have issues with fuel and the carburetor, but it seems I have no spark. I hook up my in-line spark plug tester and nothing.

Using the steps at this B&S website (How To Test & Fix Ignition System Problems | Briggs FAQ) I disconnected the spark plug wire from the spark plug. I then connected my spark plug tester to the spark plug wire. The other end of my tester, I used alligator clips to connect it to a bolt on the engine, to ground. I then turned the engine over with the pull rope and my tester showed spark!

I'm confused as to what this is actually telling me, other than the coil seems to be OK. So if I reattach my tester to the spark plug, no spark. But connecting my tester to ground, I have spark. I don't get it??? I used the old spark plug and purchased a brand-new one, same issue.

Does this have anything to do with the key with a single wire going to it? I disconnected the wire from the key, no difference. The wire looks good (doesn't appear to ground out anywhere) until it disappears behind the engine flywheel (as shown in pic) I don't know where it goes or how to access (do I need a flywheel puller?). Where does it go? In the pic, coil is removed from mounting location.

If I can bypass the key or the ground wire, etc. that'd be fine. Just so I can use it soon.

Thanks,

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01-21-16, 05:03 PM   #2  
I'm trying to follow your testing logic but it appears you have a shorted spark plug.

In re-reading you replaced the plug.
What are you using for a tester ?


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01-21-16, 05:18 PM   #3  
Simply put, I removed the spark plug wire. Placed this item, Inline Ignition Spark Checker, in-line, no light from tester.

Then removed end of tester from spark plug and connected to ground. Tester blinked as engine turned over, indicating spark.

?

 
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01-21-16, 05:21 PM   #4  
I also found out by my continued searching that the wire in the photo disappears into what I'm guessing is the points and condenser, then comes back up and goes to the kill switch.

It looks like I can replace the current coil (p/n 298316) with a new solid state coil, p/n 397358 and simply cut this black wire, leaving the points and condenser behind.

 
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01-21-16, 06:06 PM   #5  
1986 was kind of a benchmark for moving the points and condenser ignitions out.

You can do that with the replacement coil (module) and leave the points and condenser in place if you want. Then you just run the single wire from the module over to the kill switch. Grounding kills the engine.

A lot of times it's difficult to get a good spark from the plug that's visible because of not getting a good ground on the plug or trying to see it outdoors. It's a little easier in a garage.
The spark should be a bright blue spark. An orange or yellow one would be considered weak.

 
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01-21-16, 11:47 PM   #6  
That tester might be ighting because of a registered pulse, but if the condenser is leaking it might not be enough of a pulse to create an actual spark. Connecting it to the spark plug increases the resistance to ground substantially, so a weak ignition system might not have the current needed to light the tester and go to ground. A spark plug terminal is not grounded. The spark has to jump the gap at the electrode to ground. If there isn't enough energy there to do that, it won't spark.

I'd put the elecronic coil on it and connect the kill wire and be done with the points.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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01-22-16, 11:44 AM   #7  
Thanks guys, that's what I'm guessing, a very weak spark. So I've just picked up a electronic Magnetron coil for it locally; I'll be going out soon to replace it and let you know how it goes!

 
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