Intermittent Spark 1972 Mercury 402 40hp

[Cpen]

I am not sure what is exactly wrong with the motor. I have replaced the starter, starter solenoid, kill switch, ignition switch, spark plugs, and spark plug wires. It has an intermittent spark. Sometimes I have no spark sometimes I do. I have unhooked the rectifier and tried to start it and same issue sometimes I have spark sometimes I don't. I have a Fluke multi-meter and tested the stator I am only getting 100-110 volts and I think that I am supposed to be getting 180 volts. But if the stator is bad would it ever spark at all? Any advice or suggestions would be greatly appreciated. Thank you

 

[merc850]

A bad trigger will cause intermittent spark, it's under the flywheel; I think that you should check the coil grounds as well. Don't run it with the rectifier disconnected or you'll burn out the charging stator.

 

[Cpen]

CDI troubleshooting page and other outboard mechanics told me to check for spark with the rectifier undone. Coil grounds are fine I replaced most of the wiring awhile back. The trigger and stator are the issue I believe. When I check the trigger I get nothing and the stator puts out low voltage.

 

[CharlieB]

Are you using a DVA Meter and testing exactly as directed in the CDI Guide?

Regular volt/Ohm meters will NOT work correctly unless you are using a DVA Adaptor.

What is your location? Are you near another member that has the correct meter?

 

[CharlieB]

We 'Old Timers' have a method of testing that works long before DVA testing came about. but we don't post it as one small error will garbage parts.

It is unlikely for BOTH your stator and triggers to both fail at the same time. Unless struck by lightning. And that can happen on open water. But not very likely if you are still here to tell about it.

Verify your tools, and testing procedure.