1978 85hp Evinrude still runs after key is off

[soggybritchesbait]

The motor was turning off just fine until I ran it a while, got back to the dock and it took about 30 seconds for the engine to finally go off after turning the key off. It was tilted a bit so I tilted it down completely now it goes off after about 15 seconds. What causes this to happen?

 

[tashasdaddy]

Re: 1978 85hp Evinrude still runs after key is off

probably dirty connection black/yellow wire is the kill circuit.

 

[ezeke]

Re: 1978 85hp Evinrude still runs after key is off

A black ground wire runs from the engine block through the harness to your control where it connects to one of two "M" connections on the ignition switch. The other "M" connection on the ignition switch has a black and yellow wire that runs back to the power packs. When the ignition key is turned to off, the "M" circuits are made, grounding out the powerpacks. The engine stop should be virtually instantaneous.​

Clean the ground wires on your engine block and check the Red Plug for corrosion. Track the black and yellow wire and make sure that it has no breaks. You could have a loose wire at the switch, or a bad switch.

BTW, Don't apply any voltage to the black and yellow wire.​

 

[Joe Reeves]

Re: 1978 85hp Evinrude still runs after key is off

(Ignition Kill Circuit)
(J. Reeves)

A Black wire (ground) should lead from the powerhead to the powerpack. There will also be a Black/Yellow wire leading from the powerpack to a raised "M" terminal of the ignition switch. To complete the circuit, there will be a Black wire from the other "M" terminal of the ignition switch to ground.

When the key is in the OFF position = The two "M" terminals are connected,. effectively shorting/killing the ignition.

When the key in ON position = The two "M" terminals are not connected and the ignition is engaged.

 

[DHPMARINE]

Re: 1978 85hp Evinrude still runs after key is off

Good replies listed above.

I just wonder if the motor was 'trimmed' too high and now runs too hot.

Hot spots keeping it running.

DHP

 

[soggybritchesbait]

Re: 1978 85hp Evinrude still runs after key is off

If this is the problem will it work itself out or is there some adjustment to be made? I was in shallow water and had it tilted for about 20 minutes prior to docking. I've allowed it to sit about 20 hours then started it again and it still took about 30 seconds to turn off.

 

[iwombat]

Re: 1978 85hp Evinrude still runs after key is off

What he's referring to is dieseling which is the fuel combusting under pressure in the absence of spark. That can happen if the engine gets too hot, or has hot spots. If you've cooled it down, and it still happens you can cross dieseling off the list of potential causes.

 

[ezeke]

Re: 1978 85hp Evinrude still runs after key is off

Dieseling is much more likely to happen in an engine that has a relatively large amount of carbon build-up in the firing chambers. If that is the condition, or if you suspect that it might be, you might want to do a thorough decarb at this time.
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