Where is the trigger on a 1970 115hp mercury and how do I test it.

Where is the trigger on a 1970 115hp mercury and how do I test it. When I go to start the motor it start just up untill I let off the key switch. The second I let off the key switch it dies. I changed out the key switch first but it was not the problem. I posted this last year and a couple people told me to test the trigger.

You might have a simple wiring problem somewhere.

Try this: Disconnect any black with a yellow tracer wires on the switch boxes and start her up. If the problem is gone, work towards the key switch to eliminate the problem. That's the 'Kill' wire, so you'll have to choke her off, or run her out of fuel, to stop her.

Jeff

PS: The trigger coil is below the flywheel and it activbated by magnets on the hub. In your case, seven wires (a ground plus one per circuit per cylinder) come from it to the switch boxes. Seeing the motor starts, that SHOULD eliminate the trigger coil as a problem.

On a 1970 motor you might find the trigger in the belt driven distributor.----Have you cleaned the distributor cap ?

So after researching a little more i found that the trigger is in the distributor. When I took off the distributor cap I discovered that the center carbon brush in the cap was broke into many pieces It's where the coil wire goes. I am ordering a new brush assembly today so I hope that is all it was. I'm wandering what would have caused this though and if this is part of a bigger issue. The whole brush and spring are broken up all over the inside of the cap.

The motor is some 40 years old.------Sounds like routine maintenance was never done on it.------Nowadays few folks take motors in for work and assume that when a motor " runs " there is nothing wrong.-You may want to inspect the water pump as well !

Sorry for the miss-info. Thought that was an ADI Merc.

Good eye on that carbon problem. Nothing lasts forever.

Jeff