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Offroad Tractor Rider!!
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289 Posts
Discussion Starter · #1 ·
I have an onan 18 that is not getting spark. It's off of a gt18 suburban. I had to disconnect a few wires to pull it off so is there something that has to be connected to power besides the starter to get spark? Like the gray wire on the coil or anything? Thanks a lot for any info. :thanku:
 

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SEARS TRACTOR COLLECTAH
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1,386 Posts
I have an onan 18 that is not getting spark. It's off of a gt18 suburban. I had to disconnect a few wires to pull it off so is there something that has to be connected to power besides the starter to get spark? Like the gray wire on the coil or anything? Thanks a lot for any info. :thanku:
Hey WvBurban, Welcome to the forum! There should be a small post terminal on the coil. All you need to do is connect a wire to the coil terminal from a 12v battery and it will fire. Unless of course the points are bad. in order to shut the engine off, Just disconnect the lead wire. Onan's use an automotive type ignition system. The coil has to be energized in order to fire. Hope this helped. - Brad
 

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Offroad Tractor Rider!!
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289 Posts
Discussion Starter · #3 ·
Ok thank you. I realized that it is more similar to an auto engine, then a lawn mower. It has an exhaust for each cylinder and a coil and wires. I was impressed, only thing negative I've read about the onan is it can be pricey to fix but once u get it running good ull nvr want to sell it. Hope thats an accurate statement.. because its a big motor and i could definitely use the power.
 

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Cranky Motorsports
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15,199 Posts
I disagree that they are pricey to fix- If you buy all new parts they are pricey- you can get a plethora of used parts off ebay and craigslist. The coil needs to be wired with the + side to keyed power, and the - side to the points. The onans NEED a battery to run as the coil needs power.
 

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Offroad Tractor Rider!!
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289 Posts
Discussion Starter · #5 ·
Oh ok well that's good to no because only spending 75 on the entire tractor I don't want to drop a big amount into it if I can avoid it.
 

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Cranky Motorsports
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15,199 Posts
Click on the "My free manuals" link in my signature- I have manuals for GT18, SS16, and 18/6 models- all are very similar. They have motor diagrams, wiring details, and general tractor info including part numbers
 

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Offroad Tractor Rider!!
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289 Posts
Discussion Starter · #7 ·
For some reason it won't let me download it..
 

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Offroad Tractor Rider!!
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289 Posts
Discussion Starter · #8 ·
Never mind its working now. Not sure wat was wrong
 

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20,000 +posts!
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While its true the Onans used on Sears tractors have a 12V coil,some of the others had a magneto ...my Lincwelders CCKA 16 HP Onan has a magneto ,it needs a battery only to spin it over,the magneto needs no outside current source to create spark....
 

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Offroad Tractor Rider!!
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289 Posts
Discussion Starter · #10 ·
So the onans with a coil, do they have a alternater?
 

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SEARS TRACTOR COLLECTAH
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1,386 Posts
So the onans with a coil, do they have a alternater?
All Onans with electric starting feature a charging system. There is a stator under the flywheel that recharges the battery. It has the same principals as an alternater, But it's more like a generator. Instead of using alternate current, It directly charges. - Brad
 

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Offroad Tractor Rider!!
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289 Posts
Discussion Starter · #12 ·
That's frkn sweet. Thanks a lot guys for all the information.
 
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