Coil testing

PTmowerMech

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AST 1200 watt Generator, Model GG1200. Engine stamp #JF15FEH-2 (I think)

So I'm getting intermittent spark. Cleaned the flywheel and am bench testing the coil, Am I'm getting a reading as if it's good. Except from A (where kill wire connect to B (the bases where you put the feeler gauge when installing it) I get a reading there. But the numbers are all over the place. And I have to keep moving the leads otherwise it goes to zero. As soon as you move it, the resistance jumps up, then back to zero when I stop.

With the meter set ohms on 200
C- to A+ 10.2
C- to B+ 10.17
B- to A+, It jumps up, then back to 0.00. Note, if I turn the meter to 200, I get a steady 1.3

Is this just a bad coil?

Note: I've tried yelling at it, cussing it. and even threatened it so far. So, I'm guessing the coil is deaf.
 

PTmowerMech

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After testing it, as I described about, I put it back on and got fire. Tested the spark plug against the block and it was sparking good. Checked the compression and I'm getting a little over 70lbs. But won't start.
Pulled the flywheel off, and the key was good.

I've got compression, spark, air, and fuel (using carb stray into the carb. And all it does is spin over. I got a couple of coughs back out of the carb. But only a couple after turning it over 100 times or more.
 

Hammermechanicman

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Plug against the block not a good test. Remove spark plug and see if you can get 1/4" spark from plug wire to ground. If it is the original plug from a Chinese engine replace it with a champion or NGK. Just because you get a spark on an .030 gap on a plug does not mean the plug or coil is good. Briggs has a good cheap gap tester part no 19368. The neon ones inline with the spark plug will show spark but not a bad plug. Anytime you are fighting a nonstart problem test the coil with the 1/4" gap spark test and install a NEW spark plug. Don't guess at what might be wrong. Eliminate the ignition system then move on from there to fuel and compression. I have seen the chineese plugs do some weird stuff. Nothing leaves my shop with chineese plug in it.
 

bertsmobile1

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It is a bit klunky but I use the red neon spark tester because the red is easy to see.
However between it & the plug cap I use a moving electrode spark tester set to 1/4 " initally and from there I increase the gap to 1/2"
If it wont throw 1/2 " then it is bin time.
This is of course after the coil comes off & gets the ground contact points cleaned and if it has a visible ground wire, it get checked as well.
The cheap & nasty version is a plain strait clear biro case.
Cut off the small end then shove some HT lead in either end till it has a 1/4" gap between the wires.
Insert this between the plug & the plug cap on the coil.
Also try removing the plug cap if it has one.
Not uncommon to find the last 1/2" of HT wire totally corroded back up the insulation so you have in effect a 20K resistor cap as the spark is traveling through copper oxide not copper wire.
 

PTmowerMech

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It is a bit klunky but I use the red neon spark tester because the red is easy to see.
However between it & the plug cap I use a moving electrode spark tester set to 1/4 " initally and from there I increase the gap to 1/2"
If it wont throw 1/2 " then it is bin time.
This is of course after the coil comes off & gets the ground contact points cleaned and if it has a visible ground wire, it get checked as well.
The cheap & nasty version is a plain strait clear biro case.
Cut off the small end then shove some HT lead in either end till it has a 1/4" gap between the wires.
Insert this between the plug & the plug cap on the coil.
Also try removing the plug cap if it has one.
Not uncommon to find the last 1/2" of HT wire totally corroded back up the insulation so you have in effect a 20K resistor cap as the spark is traveling through copper oxide not copper wire.

Everything was pretty clean. Especially the coil. The flywheel had minor surface rust on it. One swipe with a small wire brush, and I could see metal. The metal surfaces on the coil had virtually no rust.

Moving electrode spark tester? You mean one of these?
1581823550955.png

The coil going bad was something I considered. But after installing it back on, checking the spark against a ground, and with the testers I've been using, and getting good spark, a coil going bad is still a big possibility. Except for it not hitting a lick.

What do you mean by "bios case?"


When I ordered the carb for this, It came with a new plug. This engine is an OHV. The plug is long, like an OHV, but the threads are shorter than most. I don't recognize the brand name on the plug.
 

Hammermechanicman

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I think he means one like this. I have this one and it works fine.


Most plugs that come in an ebay carb kit have junk plugs. If they say Torch, Arnold, NHSP, jenn feng, Meiya, JS or a bunch of other names i would chuck them in the bin. After 50 years of working on various engines I stick with name brands. Champion, NGK, Bosch, Autolite. In my shop i only stock champion and NGK. If you get a Chineese Honda clone use an NGK BP5ES or BP6ES depending on the engine.
Biro. Clear plastic case from an ink pen.
 
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bertsmobile1

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yep,
That is the animal
The 3 electrode Briggs tool is very hard to read because you are looking for a blue-white spark against a transparent window.
The variable gap one has a black background so the spark is easier to see and thus it is easy to see when it stops.
I have a slightly better version where the HT connection near the adjuster ( red knob ) is covered because these will bite when the gap is too big to ground through the plug, it will ground through you.

And yes a typo with Biro.
back when Bic invented that first clear tube Biro there was a flurry of bodges printed in motorcycle magazines to do what I had described to overcome fouling plugs & failing magnetos.
Every now & then you will see a "spark intensifier" which is a tube about 2" long with a screw at each end .
You are supposed to cut the HT lead & insert the "magic box" into the HT cable, Inside there was nothing more than an air gap and people paid $ 20 by the thousands fr one of these miracle mileage increasers.
 

Hammermechanicman

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I took some black electrical tape and covered one side of my briggs tester to make it easier to see the spark.
 

PTmowerMech

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I'm not having a problem seeing the spark in this tester. Same as touching the plug on the block and turning it over. Plenty of spark since I put the coil back on. But the spark could be brighter. It does seem a little dim.

The name on the plug is "Torch E7RTC." I need to cross reference this to see if it's the right one.
 

PTmowerMech

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I think I've found the problem. The cordless drill I was using to start it, wasn't creating enough RPM's for it to fire off, I suppose. I just put a fresh battery in it, and after about 20 seconds, it fired off and ran for about 30 seconds and died on it's on. Got out my other drill, with a cord, (more PRM's) and it fired off quick. Ran for about 30 seconds again and died.
Disconnect the kill wire, and it stays running. I guess I have a bad oil sending unit.

Thanks everyone for your help.
 
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