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Motor won't shut off with key - 1961 Evinrude 40hp 35524

J

joshc83

New member
Hi all,

New to this forum and to boating in general. Last year I picked up a 15' 1975 MonArk with a 1961 Evinrude Lark III 40hp, model 35524. I've re-wired the boat (minus engine wiring), replaced the steering cable, rebuilt the lower unit, had it tuned it up, etc. It seems to be running well although I've only had it out on the water once so far (steering cable broke after about 15 minutes). I've attached some pics of this fun little project.

I have a problem that has me stumped. The motor won't turn off via the key so I have to throttle it all the way down to kill it. Replacing the ignition switch didn't solve it so now I'm tracing wiring and checking for continuity, etc., but I've reached a point where I don't know what to look for.

If I understand correctly (big if!), there are two wires connected between the ignition and the magneto, one of which is grounded to the powerhead. In the "off" position, this circuit is closed, grounding the line so that no spark is delivered to the plugs. I have verified that one of these lines is grounded to the powerhead and the other is not. I've also confirmed that the ignition switch is opening/closing the circuit properly. I am a bit confused by the wiring diagram in the service manual (attached). It shows two lines, each connected between the ignition switch and one set of points, but I don't see that either of these are grounded to the powerhead in the diagram. It seems maybe this wiring diagram isn't telling the whole story (e.g. where are the plugs and plug wiring?).

Obviously I'm missing something here. I need a better understanding of what I'm looking for and where to find it. Any help is greatly appreciated!


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Those 2 black wires should kill the motor when they are touched together ( what the ignition switch is doing) or connected to ground. From the diagram it looks like one is connected at the cut off switch.. both should be connected to the points though is what I’m seeing.
 
But yes I agree I don’t think one of the wires should be grounded to the power head.. looks like one comes straight from the points and other one attaches at the cut off switch.
 
The diagram is correct. Look at the breaker points. See the two black wires? One goes directly to the ignition switch. The other one also goes to the ignition switch but the vacuum cut-off switch is also connected into that wire. Just ignore the vacuum switch for this. That is for another purpose and has nothing to do with the ignition switch. I don't understand where you are seeing either of the black wires grounded, and indeed they should not be grounded. Yes, connecting the two black wires together (by turning the key off) is what stops the motor. NOT by grounding one of them.
 
I believe he was saying he’s confirmed one of the wires was grounded to the motor but did not see anything grounded on the diagram.
 
Spence648 said:
I believe he was saying he’s confirmed one of the wires was grounded to the motor but did not see anything grounded on the diagram.
Click to expand...

If that's what he's saying, it is still wrong. Neither wire should be grounded to the motor. However, ​if checking it with a continuity meter, yes it can show continuity to ground through closed breaker points and coil primary winding.
 
fdrgator said:
If that's what he's saying, it is still wrong. Neither wire should be grounded to the motor. However, ​if checking it with a continuity meter, yes it can show continuity to ground through closed breaker points and coil primary winding.
Click to expand...

Thanks for the replies. Yes I was checking continuity and one "M" terminal on the ignition switch shows continuity with the powerhead while the other does not. Is that what you would expect to see when the switch is in the "run" (open) position?
 
Well actually, it should show some continuity in both wires, Under ideal conditions, there should be zero resistance if the breaker points happen to be closed. BUT the points are paralleled by the coil primary winding which is around an Ohm resistance, which you are going to see as "continuity". If you want to make a meaningful continuity test, disconnect the wires at the powerhead and check continuity of the isolated wires alone.
 
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