1989 70hp Mercury ignition

[jd438]

I bought a '89 Mercury 70hp engine that has been sitting for 2 years. When I got it hooked up the engine will crank, but I have no spark on any of the cylinders. Then I started looking around and have a few extra wires that look like they would go to a warning horn and maybe a tilt/trim gauge. One was a purple wire that had a pigtail on it and said(ign.) I have a feeling that I may just have a switch problem that is not turning the ignition on when I turn on the key. Also I have the oil resivior disconnected, that wouldn't have anything to do with it, would it? I have looked through my book and I am confused on where to start checking. Any suggestions?? What wires should have voltage, or should I be checking ohms?
Any help

 

[Laddies]

Re: 1989 70hp Mercury ignition

Disconnect the black yellow wire from the switch box and check for spark if you don't have spark then you will have to test the ign. system. Don't on any reason hook any voltage to the system it will burn something out!

 

[jd438]

Re: 1989 70hp Mercury ignition

I show two black and yellow wires going to the switch box, one from the controls and one from the mercury switch and they may be on the same terminal. Should I disconnect both?

 

[jd438]

Re: 1989 70hp Mercury ignition

Ok, I diconnected the black and yellow wire, and I have spark. What should I do next?

 

[Laddies]

Re: 1989 70hp Mercury ignition

If you did both, then hook the key back up and check for spark to see if the problem is in the control wiring or the mercury switch.

 

[jd438]

Re: 1989 70hp Mercury ignition

They actually have both on one terminal. They don't seperate.

 

[jd438]

Re: 1989 70hp Mercury ignition

I got them seperated. Had spark when the controls were attached. Thought for fun I would try hooking up the mercury switch and had spark after that too. not sure if it shook something loose somewhere or what. Still might look at replacing that switch I don't want to be out on the water and something to not work. I need to replace some fuel lines and try to fire it up tomorrow.
Thanks for the help.

 

[gogono2]

Re: 1989 70hp Mercury ignition

before you go buy a new switch unessarily, you might consider getting a crank test by a pro. The books have the procedure at less than hour of labor at about $65 bucks. It might be worth it since you cant return electrical parts. Or you can always go by a DVA meeter and crash course voltage readings. I had the same intermittant spark issue and it turned out to be a bad stator (which was brand new) and a bad trigger.