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Old 04-11-2012, 03:31 PM   post #1 of 12
homefried1
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Default onan coil

Got back to work on my sears gt18, and got it running. Today I was gonna put a generic vacuum fuel pump on it, but when I tried to crank it, it wouldnt fire. Got out my test light and checked the coil, no fire on the points side. It should light a test light on both the hot side and the points side shouldnt it, when you turn the key to start?

Anyone know where to get one for less than an arm and a leg? It is the BG/MS 2980A engine with 2 plug wires in the coil.
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Old 04-11-2012, 03:40 PM   post #2 of 12
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Default Re: onan coil

I've heard that you can use the coils off of certain Harley motorcycles, I have a butchered Onan B series engine that has a coil from a Harley Davidson. You might want to check auto wreckers or anywhere else that deals with used motorcycle parts, if your problem is the coil.
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Old 04-11-2012, 04:40 PM   post #3 of 12
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Default Re: onan coil

I have never had a bad Onan coil yet- try filing and resetting the gap on the points, then check for spark. If that doesn't work, I think a Harley coil will work, or troll ebay for a used Onan coil
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Old 04-11-2012, 08:07 PM   post #4 of 12
homefried1
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Default Re: onan coil

Quote:
Originally Posted by lobsterbox View Post
I've heard that you can use the coils off of certain Harley motorcycles, I have a butchered Onan B series engine that has a coil from a Harley Davidson. You might want to check auto wreckers or anywhere else that deals with used motorcycle parts, if your problem is the coil.

Yeah, a harley 45 coil would probably work, they both have the wasted fire sysytem where both plugs fire everytime but, wouldnt that most likely cost more than a new onan?

I thought about two 12 volt coils off junkers, wired together might work.OR, wonder how hard it would be to take one regular coil and make a wire with one end at the coil, and two ends to go to the plugs?
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Old 04-11-2012, 08:09 PM   post #5 of 12
homefried1
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Default Re: onan coil

Quote:
Originally Posted by GT_80 View Post
I have never had a bad Onan coil yet- try filing and resetting the gap on the points, then check for spark. If that doesn't work, I think a Harley coil will work, or troll ebay for a used Onan coil
Wouldnt it light up a test light at both the hot side and the points side where you turn the key on, if the coil is good?
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Old 04-11-2012, 09:09 PM   post #6 of 12
Plowthesidewalk
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Default Re: onan coil

If you have an Ohm meter you can do a resistance check on your coil. Some pics of a new Harley coil follow also.
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Old 04-11-2012, 09:29 PM   post #7 of 12
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Default Re: onan coil

Quote:
Originally Posted by homefried1 View Post
Got back to work on my sears gt18, and got it running. Today I was gonna put a generic vacuum fuel pump on it, but when I tried to crank it, it wouldnt fire. Got out my test light and checked the coil, no fire on the points side. It should light a test light on both the hot side and the points side shouldnt it, when you turn the key to start?

Anyone know where to get one for less than an arm and a leg? It is the BG/MS 2980A engine with 2 plug wires in the coil.
In answer to the part I italicized and underlined, With the key on, and the points open it should light. With the points closed it will not. When cranking with the starter it should blink.
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Old 04-11-2012, 09:30 PM   post #8 of 12
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Default Re: onan coil

the - side on the coil should flash when turning the motor over if your not turning the motor over while doing it the points could be open and no pwer will be going to the - side of the coil so turn the engine slowly by hand until the points close if it lights up then your coil isnt bad it probably the condenser that either has a bad ground or needs to be replaced its rare that a coil is bad unless its rotted
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Old 04-11-2012, 09:31 PM   post #9 of 12
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Default Re: onan coil

or maybe it when they're open one or the other it should work but i think its when there closed because then you have a complete circuit
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Old 04-12-2012, 07:51 AM   post #10 of 12
homefried1
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Default Re: onan coil

Thanks for the answers, I think now I have the answer. Going by what yall have told me, I think the points are bad. I have had to file them before, I just thought though that there should be power at the hot side and the points side of the coil when the switch is turned on.

Its amazing how simple the answer usually is.
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Old 04-12-2012, 11:43 AM   post #11 of 12
homefried1
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Default Re: onan coil

Quote:
Originally Posted by GT_80 View Post
I have never had a bad Onan coil yet- try filing and resetting the gap on the points, then check for spark. If that doesn't work, I think a Harley coil will work, or troll ebay for a used Onan coil
DING DING DING!

Filed the points and got fire. Thanks for the help. One more question though, what is the point gap supposed to be?I'm gonna get a new set and dont know where to gap them.
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Old 04-12-2012, 11:47 AM   post #12 of 12
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Default Re: onan coil

I think between .019 and .021 but don't quote me- I usually just eyeball it to make sure they open a tiny bit, and I have had good luck with that. They rust up if they are open when the motor stops turning and it sits for an extended period of time. Thats why first thing I do if it doesn't have spark is check the points.
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