# 18 HP Briggs&Stratton I/C ignition



## EvilleDave (Mar 5, 2005)

I am building an airboat using an 18hp B&S I/C. I purchased a used boat and took all the parts off to transfer to my boat. I have no spark. This has the generator/starter on with a solenoid. Is there a place online I can find a wiring diagram? This engine was running but hasn't been run in a while. I can't find a model number anwhere, I found the ser # but that's it. My guess is that it is an early 90's motor but I can't be certain. There is a red and a white wire coming from the case. It looks like the white one was never used. Maybe this pic will help.


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## scrench (Dec 8, 2004)

that looks like an onan engine,,, disconnect the kill wire @ the engine and check for fire , i think if i worked on that i would take off the prop ,


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## EvilleDave (Mar 5, 2005)

The kill wire is not connected


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## bugman (Aug 12, 2004)

make sure it fires the plug with the plugs out. if not it may just be a spark problem and be a could be a few different problems, plugs, coil, flywheel key, or just a wire is not on.


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## EvilleDave (Mar 5, 2005)

I pulled the plugs and checked them using my garden tractor and they fire. There are no wires hooked up yet. I have three wires. Red an white on a plug then a wire on a terminal. here's some pics.


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## bbnissan (Nov 7, 2004)

That red and white wire looks like the harness for a fuel shut off solenoid.

BTW...the model number should be stamped in the fan shroud some where.


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## mikemerritt (Dec 6, 2004)

You need to take the blower housing off and pull the ground off of the coil unless you know the kill wire isn't grounding out somewhere. One of the plugs must be grounded while checking the other for fire. I don't think they ever made this engine with points so the check I just decribed should show (1) plugs that fire (2) the fact you need a coil if they don't. 

The red and white must be stator wires. One will have a diode on the end of the wire or run into a rectifier/regulator. This wire will charge a battery if your going that route. The other could be used for lights or not at all. 

The model number should be stamped into the blower housing or on one of the pieces of sheet metal that cover the head. 

This is a very cool engine and fairly scarce compared to its vertical cousins. Most of the parts that matter will interchange with vertical models. 

Question, do you leave the governor functional in this application?

Best of luck with your project,
Mike


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## bugman (Aug 12, 2004)

i had a apposed twin model 18hp briggs, model # should be around somewhere on the cover, plugs can fire when taken out(both of them should fire) if they don't it probablly means a wire is not connected right or the coil gap is way off or you need a new coil. the color of the engine basically sometimes means it don't have points. you also could check and see if the wires to the plugs are not too cracked and are touching metal, if they do you need to rectify the problem because it may be shorting to the engine.


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## EvilleDave (Mar 5, 2005)

I'll look again for the numbers but I looked all over areas that were mentioned. The governer stays operational,the prop is at full operation at about 3200 rpm.
Thanks for the help, Pulling the shround was the next step. Yo make sure things weren't corroded and to check the wires. Once I see that all is well there, I can move on.


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## scrench (Dec 8, 2004)

in the second picture that green wire with the blue connector looks like it might be touching the shroud ,might not be but i'm pretty sure thats the one that goes to the coil aint that the kill wire ? it might have points even if it dont that wire cant be grounded out, you can check it with an ohms meter to see if its open , just turn the engine over slowly by hand and watch the ohms meter if the ohms meter climbs and falls then points are there and are working ,or if you get infinity ohms the wire is dead shorted , if someone ran power to the kill wire and its magnatron ignition , the coil is toast , you can also check the coil with the ohms meter without taking it all apart , that might have points , in the second picture it looks like the tab with the mod# has been cut off or removed , model #'s not as important as the first 2 #'s of the code on the engine ,, that will tell us the year of it


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## bugman (Aug 12, 2004)

yeah scrench has a point, if it had in fact was shorted out, the coil is fried, also that green wire sounds familiar to me, is all the wires to the solenoid to it, some are green, yellow, etc, and when they pop off no go. also i don't think it has points on it since it doesn't look very old but do what he said if it has points, you might be able to tell when you take the shroud off and look under the flywheel and see a cup of sorts covering them. oh and any rusty or corroded wires should be replaced or if not bad cleaned up and have a good contact., plus yeah the first two numbers should give the year but the whole # is just as good


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## EvilleDave (Mar 5, 2005)

There are no wires hooked up and no wires touching anything. the wires on the solienoid are all cut except the too from the batt. and starter. I removed this from the old boat myself. Most of the wires you see are for lighting and will be removed and replaced. All I can find as far as numbers is the serial #. I'm going out now to pull the shroud.


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## scrench (Dec 8, 2004)

You need to take the blower housing off and pull the ground off of the coil unless you know the kill wire isn't grounding out somewhere. One of the plugs must be grounded while checking the other for fire. I don't think they ever made this engine with points so the check I just decribed should show (1) plugs that fire (2) the fact you need a coil if they don't. 

mike merrit said it best


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## EvilleDave (Mar 5, 2005)

Looks like no points. There was some rust and a nest in there. I cleaned it all up but still no spark. It looks like this is the only thing it could be. I unhooked the black wire from the terminal so there is no chance of it being grounded out.


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## scrench (Dec 8, 2004)

well there use to be points . that is a magnatron kit that is snapped on the coil , if i were you and wanted no problems out of the engine i would replace that whole coil with a 394891 briggs #'s the magnatron kit is good but with your application i would get myself a good magnatron coil , i dont want to tell you something that you might alreay know but dont send power to the kill wire . your picture in picture you have posted one of those wires is the accessory wire that runs lights ect. the one with the diod (the little round raised thing in the wiring closest to the engine is the one that makes it charge ,) i dont know what kind of wiring you plan to use or( key switch ) or push buttons to kill and start , but if you need any help just post ? i guess i should not say that points were there @ one time but its likley i dont think someone would put that setup on it if it was not points type but you never know , also just wanted to add verry simple to wire up


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## scrench (Dec 8, 2004)

might just be the picture but the gap looks verry close ,,

also would like to know how fast will something like that go on the water ? and is it a 14' boat , that is killer looking deal , i have seen a few with small block chevys on them , also what would a prop like that cost , it looks like its wood ?
also i think if i had her torn down that far i would pop off the flywheel and put a new flywheel key in it, there is alot of inretia there ,


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## mikemerritt (Dec 6, 2004)

I am curious how you are rolling the engine through to check for fire? These add on modules are known to take more RPM's to get fire to a plug and this coil has two. Does the starter sound like its doing all it should. These starters get dry and sloppy on the top bushing and it might sound like and look like its working well but could be off some 100 RPMs or so, thats enough to cause trouble. 

Mike


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## scrench (Dec 8, 2004)

good point , i have never tried the magnatron kit on a 2 cyl , but if it was mine i would put the one thats on it in file 13 , and get good one ,


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## EvilleDave (Mar 5, 2005)

*would like to know how fast will something like that go on the water ? and is it a 14' boat , that is killer looking deal , i have seen a few with small block chevys on them , also what would a prop like that cost , it looks like its wood ?*

I'm figuring it will do 25-30 mph. It is a 16 ft by 6 ft boat. That is a regular airplane prop made by Culver Props in Ohio. The are about $300 It is wood.

*I am curious how you are rolling the engine through to check for fire?*

I am turning it over with the starter. The starter works fine and with the prop on it turns even better.


Thanks for all the help. I'll post a pic when I get it all done. I am quite use to fabricating things. Here's a pic of my main hobby


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