1979 115 ADI no spark, everything is new.

5nahalf

Cadet
Joined
Jul 31, 2024
Messages
6
Hello all, first time posting, but I have hit a wall on my motor.
Its a 1979 115hp, had been sitting for about 3 years. All the wiring was shot, so new Sierra stator, new CDI trigger, new CDI harness, new CDI coils, new switch boxes, new starter motor.

The problem I am running into right now is that I get no spark on any of the cylinders with the orange wires hooked up.
Testing the wires with the key on shows no voltage, no continuity to ground on 2 of the wires, but 1 of the wires shows 0.7 volts and a high resistance path to ground.
Could this be a bad harness from CDI or should I be looking somewhere else?

Here is a video showing testing of the wires.
 

5nahalf

Cadet
Joined
Jul 31, 2024
Messages
6
Just went out into the garage and played around some more with the motor. I now have 1.2 volts on all 3 of the orange wires.
Should there be voltage there and if so, how many volts
 

5nahalf

Cadet
Joined
Jul 31, 2024
Messages
6
Just did a keyed switch change over since I realize that when I pulled the control box down is when I got a uniform 1.2 volts across the orange wires. So I put in a spare keyed switch, now I am sitting at 1.9 volts across the 3 orange leads with key on, and ground with key off.
I have no clue if thats good or bad, but I should be able to test tomorrow and see if it starts.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,850
When the orange wires ground they tell the switchboxes to stop making spark. Disconnect them from the switchboxes and test for spark.

If spark returns, check the wiring from switchboxes to ign key for continuity. They should not have any voltage on them and must connect to one of the "M" terminals on the ign keyswitch. When the keyswitch is in the start or run position, the 'M" terminal and the orange wires should not be connected to anything but the switchboxes.

If you get voltage on the orange wire, either the ign keyswitch is bad or you have some grounding issue, I would think. Using a voltmeter on a very low scale (milli volts) test various grounds on the motor and see if you have any voltage to the battery negative terminal.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,904
The problem I am running into right now is that I get no spark on any of the cylinders with the orange wires hooked up.
Do have spark with the wires removed? Make sure you ground those switchboxes as in vid one is not. All 3 orange wires are connected together at cowling harness so reading will be the same on wires. You really want NO voltage on those wires but up to 1/2 volt is Ok . Are those CDI/Rapair boxes?
 
Last edited:

5nahalf

Cadet
Joined
Jul 31, 2024
Messages
6
When the orange wires ground they tell the switchboxes to stop making spark. Disconnect them from the switchboxes and test for spark.

If spark returns, check the wiring from switchboxes to ign key for continuity. They should not have any voltage on them and must connect to one of the "M" terminals on the ign keyswitch. When the keyswitch is in the start or run position, the 'M" terminal and the orange wires should not be connected to anything but the switchboxes.

If you get voltage on the orange wire, either the ign keyswitch is bad or you have some grounding issue, I would think. Using a voltmeter on a very low scale (milli volts) test various grounds on the motor and see if you have any voltage to the battery negative terminal.
I will do some grounding checks today and see what I come up with. I did clean or replace all grounds. Might just order a brand new key switch also and see what happens.

Do have spark with the wires removed? Make sure you ground those switchboxes as in vid one is not. All 3 orange wires are connected together at cowling harness so reading will be the same on wires. You really want NO voltage on those wires but up to 1/2 volt is Ok . Are those CDI/Rapair boxes?
Yes I have spark without the orange wires.
The boxes in the picture are the old boxes, I was getting no spark with the brand new boxes, so I did a quick swap to rule that out. And yeah when I was testing the orange wires, the grounds were not attached. But testing for spark I had them on there.

b30pwpw.jpeg
 
Last edited:
Top