1975 Mercury 150 hp Spark Issues

[Jhenry72]

Hello,
I've got a question that I hope I can get pointed in the right direction. I have a 1975 Mercury 150 with No Spark. I have done a couple tests that I have read from other users and what I've come up with is that I have No power coming out of the green wire out of the Switch Box, which leads to the Coil. There is power going in. So, is there another direction I need to look or am I looking at replacing the Switch Box? Also, is there a way that I can check to see if the switch box is faulty? I have also heard to check the Trigger, or Timing Ring? Not really sure where to start looking for those...?

Any help is Very Appreciated! Thanks!!

 

[Chris1956]

Re: 1975 Mercury 150 hp Spark Issues

The CDIElectronics web site will have a test for the switchbox. The green wire will get a pulse of voltage, when the switchbox wants to fire a spark plug, but the voltage will likely be unreadable.

You must have +12VDC on the red and white wires that go to the switchbox. Without power on those, you will not have spark.

 

[Jhenry72]

Re: 1975 Mercury 150 hp Spark Issues

Thank Chris1956! I do have power going to the Red wire. I'll check out the CDI website! Thanks Again!!

 

[Jhenry72]

Re: 1975 Mercury 150 hp Spark Issues

Well, I believe I've figured out my problem! Guess I'll be need of a New wiring harness!! Geez!!