'72 100hp Johnson Ignition question/problem

Joined
Jul 5, 2007
Messages
6
As stated in the title I have a 1972 100hp Johnson....picked this motor up locally for a couple hundred bucks....here is what i found on my initial once over
  • 105 to 110 compression on all 4 cyl's
  • newer CDI 113-8362 pulse pack (looks like within a year)
  • ignition coil replaced with pack
  • newer stator and rectifier
  • carbs cleaned/rebuilt
  • newer pickup sensor in timing base
  • new wires
  • new plugs

the previous owner must have changed all these parts to try and eliminate the problem he was having....there is still a problem within the ignition system as far as I can tell.....

When I pull a plug wire and check spark...it is real erratic about firing.....all 4 cylinders do this....when you crank the engine...it is almost like there is a timing problem....runs badly for 30 secs or so and quits, but will crank right back most of the time....pull the plugs after this and they are a bit wet/oily...the stupid thing sometimes kicks backs and cranks backwards (and from what I see, is electrically NOT supposed to happen) and runs a bit smoother backwards than the correct rotation.....ALSO...I did read (CDI troubleshooting guide) "Make sure the triggering ring is the correct one for the type ignition being used. Phase II ignitions require the sensor with wide gaps between the lobes". there were drawings of the 2 different rotors and I have the Phase I rotor....

My question is how do I know which Phase ignition I have????? and how much will this affect the timing if my ignition is Phase II??

I have purchased a manual...should be here in a few days. I also ordered a spark gap tool and DVA adapter for my meter.....any suggestions in the meantime would be great....
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: '72 100hp Johnson Ignition question/problem

If that is a phase two pac, It should have a 1/2" tooth, 1" gap on the rotor This is a battery CD ignition, if it will run backward's. it has a missing, or broken anti-reverse spring. But to run backward's, it has to be firing out of time. Has the distributor cap, and rotor been replaced? Has the safety clipper been removed as it should have been if the pulse pak, and coil has been replaced? This can be a difficult system to trouble shoot, if you have'nt been around them. There are two rotor's, the sensor, as stated above, and the ignition, firing the plug's.
 
Joined
Jul 5, 2007
Messages
6
Re: '72 100hp Johnson Ignition question/problem

From the looks of it, the distributor cap has been changed with a SALVAGE one....it has yellow paint pen writing on the cover that says what it fits....and the safety clipper has been removed...the spring is still in place, but the contact point for the 2 wires was cracked.... the rotor button looks ok...but going with "not been changed"...but I'm not sure

Update....AAAhhh...I see a small crack and carbon trace in the top end if the cap just beside of the coil ***.....and my cap part number is 383520 and the OMC manual says 383522....not sure if this will make a difference or not...

and BTW...this is the first one of these I have ever seen....so i will need some help on this one...lol
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: '72 100hp Johnson Ignition question/problem

A carbon track could make it fire out of time.
 

hoeser

Petty Officer 1st Class
Joined
Jun 18, 2006
Messages
253
Re: '72 100hp Johnson Ignition question/problem

Check flywheel key, it may have sheared and rotated... that will screw up timing as well.
 
Joined
Jul 5, 2007
Messages
6
Re: '72 100hp Johnson Ignition question/problem

just checked the key....everything OK there.....had my fingers crossed :(
 
Joined
Jul 5, 2007
Messages
6
Re: '72 100hp Johnson Ignition question/problem

just completed the CDI test where you take the trigger/sensor leads loose and strike them together rapidly.....Pulse pack make a buzzing noise anyway....but it would not fire every time I touched the leads and the "Buzz", the Pulse pack makes, would change sound or stop all together during this test.....need some insight before I buy a new pack.......I can give more info if needed.....HELP!
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: '72 100hp Johnson Ignition question/problem

I test these paks with a peak reading volt meter, but Joe Reeves has a post about using a single filiment 12 volt bulb.
 
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