1987 70hp mercury was running great then just stops and now no fire.

[cobraxrr]

Hi I hope i can get some help with this issue. I was running my motor on the river and when in throttled back to nutral the motor just went dead and now wont fire. I pulled the spark plug wires off of each cylinder and tested for spark but none of them were fireing. please help.

 

[dpmsgeek]

I would check the kill switch wire on the switch box. CDI has has a great guide on their website. Could be a bad switchbox or stator. A DV adapter is pretty much a must for doing any other diagnostic work. I wasted a ton of money just being a parts changer before I got the DV adapter and found my gremlin.

 

[s.hadley81]

^^^^this. I had mine quit on me the same way and it turned out to be the kill switch wire, disconnected it and it fired right up.

 

[Pusher]

You just disconnect the kill switch to bypass it?

 

[dpmsgeek]

Depends on the motor. Some are normally open to kill some are normally closed. Most merc's I've worked on use the switch to ground out the swichbox so you would just remove the wire.

 

[s.hadley81]

I'm not 100% sure of the color wire that goes to the switch box for the kill switch on an 87 but I wanna say it's yellow. Don't quote me on that because it's been awhile since I played with an older merc outboard. Give this a look it will probably be a help! Click on the troubleshooting link and follow the directions to down load the troubleshooting guide.

 

[johnbatman520]

Hi. I have a 1987 70hp 3 cylinder. On mine, the kill switch wire is black with a yellow stripe, If the kill switch is at fault, by removing this from the switchbox it should start back up.
It's quite possible that this is at fault seeing that you lost spark on all 3 cylinders.
The switchbox on these are a very weak point and I have replaced 2. First time I lost spark on 1 cylinder and the second time I lost spark on 2 cylinders.
Bear in mind also that there is a switch in the control to prevent you from starting your engine in gear, that might also be worth looking at seeing that it happened when you put it back into neutral.
Might be no harm disconnecting the harness plug and seeing if you get spark back.
Hope this might help you a bit!