Re: [OMC-Boats] spark

From: Ethan Brodsky <brodskye@...>
Date: Tue, 11 May 2010 15:41:45 -0500 (CDT)

The reason for the ballast resistor is to increase the life of the coil.
Running a coil at 12V continuously can cause it to burn out, so it's
desirable to run it at partial power. Thus 12V typically goes from the
ignition/key switch, through a fuse, through the ballast resistor, through
the coil, and to ground. However, when the engine is being started
("cranked"), very strong spark helps with getting the fuel to light off the
first time, so the ballast resistor is bypassed and the coil is run at 12V.
So a wire goes from the starter directly to the coil.

If you're concerned that your ballast resistor is faulty, you can bypass it
by putting a jumper wire between the terminals. However, a burned out
(open) ballast resistor will typically lead to an engine that'll start just
fine (in the "crank" position), but stall as soon as you stop cranking it
(return the key to "run"). I'm not good with coils, but I wouldn't think
that the particular choice of coil would matter a ton - they're fairly
interchangable. The wrong coil might overheat or fail quickly or cause the
engine to run roughly, but you should at least get some spark.


On Tue, 11 May 2010, jd wrote:

> ok perfect - now I atleast know what to specifically ask for at NAPA.
> I'll get that exact coil, print out your email, get out my wiring diagrams,
> and see what happens.
> Just to clarify the photo with what you said about the pertronix. As you
> can see from the photo - that purple wire going to the ballast resister is
> coming from the dash area from what i remember. it's the hot wire from the
> ignition. on the other side of the BR is the red wire that goes on to
> connects to the pos terminal of the coil. This matches what the manual
> diagram says. However, maybe I have the purple wire from the ignition
> going to the wrong end of the BR? But does it matter which end - doesn't it
> drop the voltage down no matter what end you're connected to, as long as it's
> the opposite end? Anyway, maybe that's wrong.
> But beyond that - you said ".if memory serves the pertronix kit is a 12VDC
> system the red wire from that kit should be on the 12VDC side of the ballast
> resistor (so the distributor wiring is going to be a little different from
> the diagram)" . I'm looking at the photo, and It looks like I have my red
> from the distrubutor going straight to the pos of the coil.......which is
> getting power from the 9.5v side of the BR, isn't it? So maybe I need to
> connect that red distributor wire straight to the terminal on the BR where
> the purple wire is instead? If I'm understanding this right that would be
> the 12v side? Maybe that's the whole prob - the distributor has been
> getting 9.5v juice instead of the 12v juice it needs?
> The part I don't get is this: So 12v comes from the ignition, goes through
> the BR which drops it down to 9.5v, then on to the coil which boosts it back
> up to 20000v ? Why the BR?
> I'm with you on the wiring....which is why I spent most of last summer
> rewiring everything in my boat too. So i'd estimate my wiring in engine and
> general boat to be about 95% new. I'm pretty sure I replaced all wires
> going to the coil. Atleast back to just short of where they went into the
> plug. Plus I park it inside all winter. So I doubt i have any corrosion in
> the wiring going to the coil. Maybe inside the coil, but not outside.
> BTW - I have a multimeter but barely know how to use it. The instructions
> are a mile long, and there's about 15000 different settings on the front.
> But I'll see if I can get somehwere with it. I think mine is similar to
> this one in the photo - where should I have that dial set? Which of the two
> jacks at the bottom should I have the red test probe plugged into?
> On May 11, 2010, at 11:54 AM, BC Howk wrote:
>> JD,
>> First thing first IF you decide you are gonna use a CAR part, ask for the
>> part off of a 1969 Jeepster Commando with the V6...I used to own one of
>> these it is the SAME motor, and this is the one I use to point the guy at
>> NAPA to the part I want for my Sportsman.
>> CAVEAT: Like you I am not a professional mechanic. Through plenty of trial,
>> error and research I have managed to get my Sportsman in pretty sound
>> mechanical shape and learned a few things on the way.....I do not have all
>> the answers. You however are not alone out there, I offer whatever advice
>> or help I can :-)
>> have never replaced the coil on mine so I have not been through this
>> personally, but as I see it, there are 2 ways to go here...BTW- I highly
>> recommend picking up a multimeter too, doesn't have to be fancy but should
>> be able to read ohms and DC/AC voltage. It really does come in handy for
>> this sort of thing...
>> 1. Buy a coil for a 69 jeepster and put it on there....triple check how you
>> have the coil wired up by the wiring diagram...if memory serves the
>> pertronix kit is a 12VDC system the red wire from that kit should be on the
>> 12VDC side of the ballast resistor (so the distributor wiring is going to
>> be a little different from the diagram)...if you picked up the multi-meter
>> you should be able to check the voltage on both sides of the ballast
>> resistor to verify it is working (they don't always LOOK bad even if they
>> are)
>> 2. Buy a 12VDC generic coil of the same dimensions and hook it up (I'm a
>> little foggier about how EXACTLY to do this without really staring at the
>> wiring diagram) IF my memory serves, should hook up just like the old one
>> but connect to the 12VDC side of the ballast resistor instead of the 9.5VDC
>> side....PLEASE check the diagram and validate for yourself...hopefully the
>> new coil will have a wiring diagram in it.....
>> Hard to tell from the picture but everything LOOKs connected....If it were
>> me, and believe me I've been through this on my own Sportsman...I would
>> physically touch and trace every wire connected to the coil and compare it
>> to the wiring diagram, looking for brittle insulation, broken or frayed
>> wires, corroded connections, etc. etc.....BTW- chasing thes things down,
>> finding and patching those cruddy old wires prompted me to TOTALY replace
>> the wiring in my engine bay, by rebuilding the engine harness MYSELF, using
>> the same techniques, old harness labeld one wire at a time then removed,
>> lay it out on the floor, replace everything (had to reuse the rubber
>> harness connector), one wire at a time verified against the diagram. I was
>> an electronics tech in the Coast Guard for 10 years and am still a
>> technical guy, so wiring or troubleshooting an electrical issue doesn't
>> scare me but going through the process I learned tons about my boat and
>> haven't had to mess with wiring since; except for a stereo :-) Lot's of
>> people get freaked out about's not that bad, just relax,
>> take your time and label EVERYTHING.
>> Totally respect your desire to not only FIX your boat yourself but to learn
>> about it in the process. The offer stands if you need a hand. Happy to
>> help, share any knowledge I have stumbled across on my own and get a chance
>> to check out another OMC boat in the area.
>> Cheers,
>> B.C.
>> May 11, 2010 09:57:32 AM, jdood@... wrote:
>>> yeah you might be on to something here. here's the situation with
>>> the coils. ran it last year with a Napa coil (can't remember exact
>>> # but i think 907). Thinking it might be bad, took that coil into
>>> Napa for replacement. They could find the coil i had in their
>>> system. So then we did the wild goose chase of me telling them to
>>> check a " '70 or '71 Buick Skylark, or maybe a Kaiser Jeep V6
>>> Odd
>>> Fire Buick 225 CID 155". (I still am not clear on what to ask
>>> for but I think that's close). Also said it was from an OMC boat,
>>> etc. He came back with an almost identical looking coil, maybe #912
>>> or something. Said it was the one referenced everywhere and also
>>> said it was the common one by several other boats (bayliner, etc).
>>> So slight chance I might have wrong coill. But I checked things,
>>> tried to start, etc with my PREVEIOUS coil in there and still got
>>> nothing. But as you say, maybe that one was wrong too, but got me
>>> by last summer until it developed just enough corrosion inside to
>>> die. Especially after sitting all winter (?)
>>> 1) I don't wanna screw with this, and rely on some Napa guy thumbing
>>> through books and ending up with something that "should be right".
>>> Can you tell me exactly where to go and what exact coil I should be
>>> getting (ie whatever you and everyone else have in your boat)? I'll
>>> just go buy one. No more trial and error.
>>> 2) I have a functioning ballast resistor. I don't use any voltage
>>> meter, just my lighted screwdriver thing. The BR is getting power
>>> via a red wire to it. This is a photo i took before i went shopping
>>> for a new coil a few days ago (and so i would be able to get the wires
>>> back as they were). I hooked up the new coil this exact same way.
>>> See anything out of whack?:
>>> On May 10, 2010, at 2:36 PM, BC Howk wrote:
>>>> Sorry JD, hit send instead of save on my last I was
>>>> saying :-)
>>>> I'm certain it is something simple.....there is just no much to
>>>> these ignition systems and if you already put the pertronix kit on
>>>> there you already addressed the most complicated piece (imho)....
>>>> Just so I'm the NEW coil on there now? if my foggy memory
>>>> serves, you said you had 12VDC on the coil +....look this up for
>>>> yourself (i.e. I may be mistaken) BUT I thought that the origional
>>>> coil set up on these was 9.5 volts OR said another way your coil +
>>>> should be connected to your ballast resistor which drops the voltage
>>>> down from 12VDC to 9.5VDC...Soooo if you have a FACTORY COIL with
>>>> 12VDC on it (I think) that may be your problem?
>>>> ANOTHER possibility, if you have a NEW one there and it is a 12VDC
>>>> coil (like some high performance ones you'd see on the shelf at an
>>>> auto parts store) and you had IT connected to the 9.5 VDC side of
>>>> your ballast resistor then THAT could be a problem (9.5 VDC when the
>>>> coil expects 12)
>>>> Sooooo if you got a wire crossed and hooked up 12VDC side of the
>>>> ballast resistor to a 9.5VDC coil perhaps it could have worked for a
>>>> little while then gone kaput OR PERHAPS the inverse is true and it
>>>> sort of works having 9.5 VDC on a 12VDC coil and with just a little
>>>> corrosion, took it out of tolerance and is now giving you no spark.
>>>> Are either of these scenarios a possibility? If you are running on
>>>> the old coil and have changed nothing, perhaps your old coil just
>>>> gave up the ghost. Either way those links I sent about bench testing
>>>> a coil (I hope) will come in handy. AND might be helpful to take a
>>>> look at your ballast resistor to ensure that all the wires are in
>>>> the right place and the resistor itself is healthy.....
>>>> Hope this helps,
>>>> Cheers,
>>>> B.C.
>>>> >
>>>> >On May 10, 2010, at 10:12 AM, BC Howk wrote:
>>>> >
>>>> >> JD,
>>>> >>
>>>> >> If you have the little spark plug thingy that lights up when the
>>>> >> plug fires..then you already know you do not have spark, right?
>>> If
>>>> >> you are curious if you are using the light correctly, I might
>>>> >> suggest you try it on a known good plug wire, like your car/truck
>>>> >> for example....
>>>> >>
>>>> >
>>>> >yeah - i just used the light thing last year and it worked
>>>> >99.9% sure that's working - and you're right, since it's
>>> not lighting
>>>> >
>>>> >up on any of the plug wires Its looking like i have no spark. I'm
>>>> >just trying to see where in the chain it's breaking down. So I'm
>>>> >
>>>> >trying to see if anything is being sent to the distributor from the
>>>> >coil which is why i'm trying the coil wire.
>>>> >
>>>> >btw -- a few others have asked and I keep forgetting to mention - I
>>>> >already have the pertronix pointless stuff in my distributor, so i
>>>> >don't think it's a missing rotor or anything.
>>>> >
>>>> >
>>>> >> BTW- I use a timing light to check for clamp one lead
>>> to
>>>> >> battery positive, the other to ground, and there is an inductive
>>>> >> clamp that you clip OVER your number one spark plug wire, have
>>>> >> someone crank the engine over while you pull the trigger and viola
>>>> >> if you see the strobe your in business.
>>>> >
>>>> >So in theory I could use clamp that inductive wire to the coil
>>>> >wire? i'm by myself - but i'm thinking maybe the cord will
>>> reach
>>>> >
>>>> >and I can turn the key and pull the trigger at the same time.
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >> NO STROBE? Pop off the distibutor cap, check the brass connections
>>>> >> on the cap for corrosion, take a bit of fine sandpaper to the
>>>> >> contacts on your points, maybe just replace the points and
>>>> condenser
>>>> >> (part at any auto place, ask them for points and condenser from
>>> a
>>>> 69
>>>> >> jeepster with V6 OR get the pertronix kit PN#1165 jeep 225 odd
>>>> >> fire).....I have a sneaky suspicion that a little cleaning of
>>> the
>>>> >> contacts on your points and you will be right as rain
>>>> >
>>>> >unfortunately no, first thing i checked......pertronix contacts are
>>>> >looking clean and shiny.
>>>> >>
>>>> >> I have had the same experience you are describing basically every
>>>> >> year until I put on the pertronix kit. my timing light is THE
>>>> TOOL I
>>>> >> used to diagnose this easily, besides you will need one to properly
>>>> >> tune you boat (on mine TIMING makes a HUGE difference in
>>>> performance)
>>>> >>
>>>> >> We're in the same town...if you'd like a hand let me know.
>>>> >
>>>> >yeah thanks BC - i'm thinking i might take you up on that offer
>>> here
>>>> >soon if I can't get it. I'm going to try a little bit more
>>> on my
>>>> >own. This boat is about 95% "fixed" at this point. All last
>>>> >
>>>> >summer I spent chasing and fixing the overheat problem. Then it was
>>>> >the little piece of metal that fell down in the cylinder so i had to
>>>> >disassemble the head, etc to fix that. Then it was a the throttle
>>>> >switch that broke apart on me and time spent fixing that. There's
>>>> >not much left to fix on this boat! As you might recall, i
>>>> >actually used it a few times last summer....and at the very end of
>>>> the
>>>> >season I started having this problem where it would just drop down
>>> to
>>>> >zero RPM's right while accelerating to plane. So I think you and
>>>> >another person suggested that might be the coil. So I bought a new
>>>> >coil this weekend, and am just trying to get the dang thing started
>>>> >for the first time this season so I can see if the new coil solved
>>>> >the RPM problem. It was starting fine last summer. All I did was
>>>> >winterize it since. Now just trying to start it up this summer and
>>>> >getting no spark for some reason. So can't even look into prob
>>> #1
>>>> >untl I get past this new prob #2. But I'm hoping this spark issue
>>>> >is something really simple. So I wanna see if i can get it on my
>>>> >own, then test out the new coil and see if that fixed the
>>>> >deceleration problem. And if all goes right I might not even need
>>>> >you. All I know is I DO NOT want to have this thing sit for
>>>> >another summer while I "self teach" my way through this last
>>> little
>>>> >
>>>> >bit of problems.
>>>> >
>>>> >
>>>> >>
>>>> >> cheers,
>>>> >> B.C.
>>>> >>
>>>> >>
>>>> >> May 10, 2010 09:04:17 AM, jdood@... wrote:
>>>> >> >ok - i can do that - ill figure out some way to sort of tie
>>> or
>>>> clamp
>>>> >> >it down.
>>>> >> >
>>>> >> > the metal of the connector is way up inside the rubber boot
>>> on
>>>> the
>>>> >> >end of the wire though and i don't think it slides back
>>> - so how
>>>> >> >close do i need to get to metal to make it arc? 1"? 1/2"
>>>> >?
>>>> >> >If I
>>>> >> >can't get a spark it might in fact be because the boot
>>> is getting
>>>> >in
>>>> >> >the way - adding another layer of confusion to my process
>>> of
>>>> >> >elimination here.
>>>> >> >
>>>> >> >
>>>> >> > btw i meant clamping the wire in place somewhere with the
>>>> >> >visegrips, not holding it :)
>>>> >> >
>>>> >> >
>>>> >> >I've seen mechanics to this spark wire arc thing on occasion
>>> over
>>>> >the
>>>> >> >years, but i've never done it myself. I always sort of
>>> knew there
>>>> >> >was something semi-dangerous about it, but never knew why
>>> -
>>>> >> >especially when all the other 12v wiring stuff in a car or
>>> boat is
>>>> >> >pretty harmless if you touch it. Now thanks to Lee I know
>>> what a
>>>> >> >coil does - basically boosts up the voltage - now makes sense
>>> why
>>>> >> >people use more caution with the plug wires. I guess the fat
>>>> >> >wire running from the battery to the starter is probably one
>>> you
>>>> >> don't
>>>> >> >
>>>> >> >want to touch also. Although there's no coil in that chain
>>> to
>>>> boost
>>>> >> >
>>>> >> >the voltage up. This is where my stupidity kicks in.
>>>> >> >
>>>> >> >
>>>> >> >
>>>> >> >
>>>> >> >
>>>> >> >
>>>> >> >
>>>> >> >
>>>> >> >On May 10, 2010, at 3:42 AM, Justin DeSantis wrote:
>>>> >> >
>>>> >> >>> probably a stupid question but how do i do it without
>>> touching
>>>> >the
>>>> >> >
>>>> >> >>> wire?
>>>> >> >>> vise grips?
>>>> >> >>
>>>> >> >> NO! Vise grips are made of bare metal. It would be like
>>> touching
>>>> >
>>>> >> the
>>>> >> >> wire. It won't kill you (probably) but you'll
>>> know you
>>>> >did
>>>> >> something
>>>> >> >> wrong.
>>>> >> >>
>>>> >> >> just lay it on the engine?
>>>> >> >>
>>>> >> >> If you can, yes.
>>>> >> >>
>>>> >> >>
>>>> >> >>> plus, we're talking about short
>>>> >> >>> little 8-10" long wire that comes off the top
>>> of the
>>>> >coil
>>>> >> >>> here........its
>>>> >> >>> not gonna reach too far and probalby won't just
>>> rest on
>>>> >the engine
>>>> >> >
>>>> >> >>> either .
>>>> >> >>
>>>> >> >> Be creative. Lay something on it to hold it in place.
>>> Use a zip
>>>> >
>>>> >> tie.
>>>> >> >> Some string. Like Roosevelt said "Do what you can,
>>> with what
>>>> >you
>>>> >> have,
>>>> >> >> where you are."
>>>> >> >
>>>> >> >_______________________________________________
>>>> >> >OMC-Boats mailing list
>>>> >> >OMC-Boats@...
>>>> >> >
>>>> >> >
>>>> >
>>>> >

<a href=""> Ethan Brodsky </a>
Received on Tuesday, 11 May 2010

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