No spark on starboard side?

1 old outboard tech · Jul 24, 2017

I have a 2004 Yamaha 150 2 stroke with carbs and oil injected (150TXRC). Last summer a couple times I lost power when first running the engine but eventually kicked in and ran fine the rest of the summer. The first time I started it this summer I found that it had no spark on the starboard side and after running it around it never has kicked back in. I have tested the charge coils, the pulser coils and main coils. All check good. note: 1 of the 2 pulser coils did check about .5 volts less than the other on a cranking output test and that was under specs by that amount of .5v( ohms test where the same 330) should be 2 volts but was 1.5 with plugs in but with plugs out went to 2.5. I don't feel this is the problem and I am not even sure if 1 coil works 1 bank and the other? I thought it was the cdi unit so I was able to get a used one and tried it. It did the same thing. Either that's not the problem or both cdi units have the same problem which I have been told rarely ever go bad. I am a 35 year OMC Evinrude/Johnson outboard tech. Unfortunately Yamaha ignitions seem to work a lot different. You can disconnect the main harness on a Evinrude, older models with red plug and the motor still runs. This eliminates the harness and key switch. So I tried this with my Yamaha and I still had no spark on the starboard side and I lost spark on the top coil on the port side. I also tried reversing the leads from the pulser coil thinking that if it did work each side it would start sparking the other side if it was the problem. Instead the outcome was when fist cranking I would have spark on the port side lower 2 coils for about 2 revolutions then no spark at all. Once again since I am not sure how this 2 coil pulser system works I am not sure this would tell me anything like it would on an Evinrude. I have been told that a short in the wiring harness or a bad ground could maybe do this. All my grounds are clean and I have wiggled the harness around while running with no luck. Also this model does not have a shift assist switch. I have read something about a test light that reads codes put out by the cdi unit. My after market service manual talks a little about this. Does anyone think this will help? Please any input on what to look for would be much appreciated. Thanks in advance.