1968 Johnson dies/car conversion?

[justinj]

I have a 1968 Johnson 100 that starts and runs beautifully only to die in the middle of the lake at mid to full throttle--as in no spark. After trying to start it in vain for half an hour, it started again after wiping the plugs, but they were only wet, not fouled. I have read that this is probably a pulse pack issue, but if you have any thoughts otherwise, please send them along.
My uncle from whom I got the boat has replaced one after another pulse pack over the years and the one that's on it is supposedly new--but unused for 15 years. I rewired the whole motor because every single wire had corrosion under the insulation and in the process cut out the diaphram/kill switch and the "thermo switch"--so they're not the problem.
I'm not in the mood to replace the expensive pulse pack only to have it go bad again, so I'm wondering if anyone has a schematic diagram of the pulse pack that I could use to troubleshoot (or build my own). Or better yet, does anyone know how I could use a car setup on this motor? An old Subaru I owned had a distributorless ignition that uses a reluctor to generate a pulse (much like the Johnson's sensor). Couldn't this pulse then be sent though a car coil and then through the distributor? Unfortunately, I don't know enough about boat or car systems to figure this out myself. I'm just surprised that I can't find anyone who has already done it.

Thanks,
JustinJ

 

[tashasdaddy]

Re: 1968 Johnson dies/car conversion?

you are correct those motor for some reason eat power pack every 2-3 years. no one that i know of has come up with a solution. i had a 69 115 that you could plan on when it was going to go. great motor other than that.

 

[larky]

Re: 1968 Johnson dies/car conversion?

have you read this thread?
http://forums.iboats.com/showthread.php?t=202202

 

[justinj]

Re: 1968 Johnson dies/car conversion?

Thanks, I hadn't read the thread. My system is the breaker-less, pulse pack version instead of the amplifier/points system. I'm not exactly sure what the sensor actually does though. Is it just a switch that conducts electricity when the lobe passes by, or does the lobe inductively generate a current in the sensor? I think that the voltage and current like a points/breaker system uses would fry the sensor. lf it merely conducts, I suppose I have to run battery voltage through the sensor to an amplifier (I'm not sure if this would work). If it generates, I'll just be running battery voltage to the amplifier.

I'm pretty sure I could work something up using the factory "sensor", but I remembered that a distributorless car system has four "sensors" and coils to get the sparks to the right cylinders. So, I still need the distributor.