Briggs & Stratton ignition question

I have an older Briggs and Stratton 3.5hp engine on a lawn edger. I am getting no spark. (has points, not elect. ign.)
I have removed the flywheel and I can visually detect no issue with the points or any obvious shorts.
Any advice on how to test the magneto armature and the capacitor?
I don't mind buying the parts, but I hate to replace a part just to rule it out.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
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have you cleaned the points and spark plug?
the condenser is cheap to replace and hard to check as it may give intermittent trouble
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The capacitor can be easily tested using a simpson meter.
Put the meter on the highest ohms setting (typically RX10K) and connect the capacitor to the test leads. The needle should blip upwards for an instant, and then fall back to infinite ohms.
If it does not blip upwards, or if it reads less than infinite resistance on that scale, it is probably bad.
The mag coil probably has three leads - one that goes to gnd, one that goes to the points, and one that goes to the plug.
You should read an ohm or so between the ground lead and the points lead. You should read several thousand ohms or so between the plug lead and ground.
If either reads dead open, then that's a fail.
If the HT lead reads low resistance to ground, that's a fail.
There are ways to measure the HT insulation of the potted coil but that requires a specialized instrument called a "megger." If for some reason the motor starts and runs fine when cold, but quits when hot and cannot be re-started, due to lack of spark, that is a classic sign of failed insulation on the HT side of the coil.
Jim
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I figured there must be a way to give it a test. As usual this NG has the best and the brightest.
Thanks.
--

Roger Shoaf

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Roger Shoaf wrote:

Bite the bullet and get the solid state ignition module. Problem solved (for the life of the engine).
Ken.

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Unless the coil is bad. If the coil is bad it still won't run.
Jim
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If you want to keep the points system they must be super clean, but you are better off spending the $30.00 and getting the solid state unit, you will never need to deal with it again. You may not even be able to buy the the older setup

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On Sat, 30 Apr 2005 17:55:52 -0400, "Waynemak"

Spend $30 on a mower that I paid $2 for, five years ago? I don't think so! Gerry :-)} London, Canada
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On Sat, 30 Apr 2005 13:46:15 -0700, "Roger Shoaf"

Normally, I clean up the points with a small piece of very fine wet/dry paper folded over to do both sides at one time, followed by clean, dry plain paper to remove debris. I also apply one drop of instrument oil to the cam follower plunger. Gerry :-)} London, Canada
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On Sat, 30 Apr 2005 13:46:15 -0700, "Roger Shoaf"

I recommend going to a solid state module as well but I disagree with the price. They run between $35 and $45 depending.
On to the points. They must be extremely clean. Sometimes they look ok but don't make contact. Also be sure that they go up and down. I was into one the other day that the plunger was stuck.
There's no real good way of testing the coil. But if the points check good then it must be the coil (unless the flywheel key was sheared but you would of noticed that when taking off the flywheel).
If it is the coil then spend the extra to go with the solid state one. There's not that much difference in price and they're much more reliable than the points.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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Wayne Cook wrote:

I've seen them cheaper than this: http://m-and-d.com/ignition_parts.html
Last month, I paid the equivalent of US16.00 for one down here.
Tom
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You're talking about the Mega-fire ignition. I've used them in the past and didn't like the results. They're ok if you're good and strong but they take a lot faster spin of the engine to give spark than either a points ignition (takes the least) or a true electronic coil. If you scroll down that same page you'll see what I mean about coil prices.
I've worked on small engines professionally for going on 25 years now and I get to order the coils at dealer pricing. But I still have to get retail for them to make any money and even after market coils list for at least $35 for the cheapest.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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wrote:

disagree
strong
coil.
I paid $40 for the B&S armature coil with integral electronic ignition a few months ago...
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My point exactly. That's average. It does depend on which model coil you have but most do run around $40. The cheapest is about $35.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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Wayne Cook wrote:

Actually I wasn't specifically meaning Mega Fire, I'd never heard of them until today. I bought a generic module that requires just a gentle pull to fire up my mower. It is only about 5/32" thick so a lot smaller than the Mega-Fire. Original lasted about 15 years.
Tom
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The Mega Fire isn't much bigger than that if I remember correctly. What you used is just a copy of a Mega Fire. They where the first that I know of.
As for the gentle pull you have qualify that. A gentle pull for you could be unachievable by some old lady. I can make a points ignition fire every time by just flipping the flywheel by hand. A proper electronic coil can be made to fire that way as well but it's not as reliable. A add on electronic like you're talking about won't even start to. In fact experimenting with the ones I did install showed that the rope had to be pulled at least twice as fast when compared to a proper electronic coil.
If you want to add on electronics to a coil I recommend using Briggs method which was a module that slipped on the coil with a hall effect sensor. These essentially turn a points coil into the same thing as a modern electronic coil. In fact they where how Briggs first came out with electronic ignitions. However I doubt they came be purchased anymore. At least I haven't tried in years now.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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Wayne Cook wrote:

I'll need to wash my mouth out after this, as I have to admit to owning an Ozzie mower, namely a Victa GTS (guaranteed to start). It came standard with a module. When I mean gentle, I mean Little Ole Lady capable. I've never seen a Briggs that could come close to easy first try starting as the Victa.
Tom
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That doesn't surprise me but I must admit that they've improved over the years. One example has to be primer bulbs. They are one of the few true improvements that's ever came up in the last few years. Most of the engines are getting worse IMHO.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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wrote:

The add-on unit I installed on my old tiller engine(which I no longer own) would spark reliably enough to start on the second pull virtually every time, and it did not take any more of a pull than the original point ignition. The only thing that would make it easier to start would be battery ignition. It started at least as easily as the mower with factory "magnetronic" ignition.
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On Sun, 01 May 2005 23:36:46 -0400, snipped-for-privacy@sny.der.on.ca wrote:

You probably didn't notice it. It's not that much a concern for anybody with any kind of strength at all. But the fact remains that it takes more rpms for that type to spark than the other style ignitions. The difference isn't enough to notice unless you're trying to fix a mower for a little old lady who can barely pull it.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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