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'78 70 hp electrical gremlin

J

Jogin

New member
Hello,

It has been a long time since I have posted on here mainly, I have left the industry due to winter lay off's up here in the norske. Any how now I am starting to get back into for side work considering some stuff my family has gone through. None the less, I appreciate any help that can be given.

Now to the story, I am currently working on a 1978 70hp Johnson, inline 3 cylinder, to put a long story short they were having starting issues. I went through the electrical and tested the solenoid along with rectifier for the not starting and inability to maintain a charge within the battery. After doing so I found out they were bad and replaced those along with the key switch. The reason the key switch was replaced is due to the key had broken inside and was not able to turn/engage correctly.

First off, I made the mistake of going with a sierra switch that seems to have one extra point on it that says I. The service manual and the origonal setup was having both the ground and kill switch on the M portion of the switch. I checked for spark while starting and there was none on any of the coils, I ended up removing the kill switch line off the power pack, after doing this it was able to start, however as we know it would shut off until i touched the wire back to the pack.

I am curious what I should do, I believe I have it hooked up correctly but am unsure, any tips on what should be done?


Thanks,

Jogin
 
Allways disconnect the battery if you short the kill wire to battery pos you will need a new powerpack it only takes a split second.
 
The 1978 70hp ignition switch normally has 6 terminals... "B", normal "M", raised "M", "C", "S", "A". Are you saying that the Sierra switch has one more?

Do not run any ground wires to the "M" terminals, run them to a ground that leads directly to the (-) of the battery.

Voltage To Powerpack Failures
(Magneto Capacitance Discharge Systems)
(J. Reeves)

The usual cause of having those type powerpacks fail repeatedly is having a very small of voltage applied to the Black/Yellow wire (Kill Circuit) at the pack. Test as follows.
Disconnect the Black/Yellow wire at the powerpack.

Insert either a ampere meter or a volt meter set to its lowest DC voltage reading between that Black Yellow wire and ground.

With the ignition key in the OFF position, observe the meter reading. Now turn the ignition key to the ON position and again observe the meter reading.

Any reading, movement of the meter needle, even a microvolt, would indicate that battery voltage is being applied to that Black/Yellow wire. If a reading is present, remove the other end of that Black/Yellow from the raised terminal of the ignition switch.

If the reading ceases to exist when the Black/Yellow wire is removed from the ignition switch, replace the switch. If the reading continues to exist, there would be a short of some kind in either the engine or instrument wiring harness.... to determine which, simply unplug the large RED electrical plug at the engine which would eliminate the instrument cable.

Note that the black/yellow wire must not have any other wire attached to it for the following reason!

Keep in mind that any accessory that has 12 volts running to it, especially when turned on, will have voltage flowing through it and trailering out through its black ground wire to complete the circuit. If that accessory has it's black ground wire attached to the "M" terminal that the black/yellow wire is attached to.... you will have voltage flowing directly to the powerpack.
 
thank you all for the help, going to get at it and see what i can find. I will keep you updated and ask other questions if need be.
 
I ended up finding that I connected the ground to the same point on the ignition key as the black/yellow (kill switch) wire. I also found that I had a pinched wire underneath the neutral safety switch mount. I forget how much a pain in the rear external wiring can be. Thank you all for the documents and written help, it solved the crime.
 
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