evinrude control key switch - wont kill motor

[1*jaybird]

1979 evinrude 75 hp. switch will not stop engine, have to choke it off. previous owner, had trouble also, switched key switch, I replaced power pack, same thing. any suggestions. thanks.

[OBJ]

Hey jaybird.....you can always throw a bucketo of water into it...... NAWWWWW! just kiddin'.For some reason the power pack isn't being grounded out. You have a black w/yellow stripe wire coming from the power pack. And a black wire that goes to ground connected to the ignition switch. When you go to "OFF", the switch cross the black w/yellow stripe wire to the black ground wire which grounds the power pack and stops the engine. Check the amphenol connectors at the power pack and make sure the Black/yellow stripe wire pin is protruding far enough from the connector to make contact. Check the engine ground is good and clean. Look around on the engine harness and wire harnes goging to the to the ignition switch for busted wires and such. Sometimes where the harnes goes into the engine, where the harness moves back and forth with the engine, you can get a broke wire. If you can find why the power pack isn't getting grounded out, you will solve the problem. If you need a wiring diagram, just visit the local library....they usually carry Selocs and Clymer service manuals and have the diagrams in the back. Keep us posted and....hold off on the water for now...Good Luck!

[1*jaybird]

thanks for the reply, I was working on another problem tonight and operating the key. then a buzzer went off in the control housing, never heard that before. it did it as I was turning the key. did it about three or four times and I cant get it to do it again. vintage 1979 evinrude control. weird. is this possibly related to the kill?

[OBJ]

That buzzer is the overheat alarm. It goes off to warn you that the engine is overheating. Look on the engine cylinder head and you will see a single tan wire coming from the head. That wire is coming from the heat sensor. There will be a black rubber boot there also. Pull this black boot back to expose the knife connector. Turn the key on (don't start the engine) and ground the knife connector to the engine. The warning buzzer should sound a steady tone as long as the connector is grounded. If it does not, check your grounds in the control box. Make sure they are clean and tight. You can check the horn by just pulling the wires off and using jumper wires, put it across a 12V battery. Every thing in the control box depends on a common ground wire that comes to the box from the engine. Check it good. It's the black wire. What kind of condition is the wireing harness in?You can also help your self out a lot by going to the library and seeing if they have a repair manual....most libraies have Seloc of Clymers. In the back of the manuals, there usually is wiring diagrams for the engines. Check it out and get a copy. It'll help you troubleshoot the problem.

[1*jaybird]

thanks for all the info. today found out that the head was getting warm but the water was cool for cooling and thewater was not coming out of the upper two dime sized holes. it was coming out of the other lower holes. when I looked at the thermostat it was open but the check valves rubbers were deformed and melted (?) a little and there was a chunk of rubber that appears to be from the impeller. so I will pick up an impeller tomorrow and start a tear down of hte lower unit to get that resolved. there is great compression of 155 - 160 on all cylinders. runs like a top until the engine gets a little warm then there is a slight miss. but not really noticeable. hopefully no other engine damage has occurred. is it safe to say that as it gets warm and the check valves for coolant are not operating effeciently and possibly the impeller is worn that is the cause for the ever slight miss when it is warm to hot? I hope so. adjusted the timing a bit and it seems to rev better now. I guess I will wait and see after the check valves rubbers are replaced and the impeller is changed. Jason