1968 33hp Johnson that Wont Die

[motorstuff]

I’m really stumped. I have been working on a boat with a 1968 33hp Johnson. The only issue I have left is that I can’t get the motor to turn off with the key. I went straight to the source and tried completing the circuit of the two black wires to ground it out, but that didn’t work either. The only way to get it to die is to remove the spark plug wires.

Any ideas? I’ve attached the schematic for it as well.

 

[tblshur]

motorstuff where did you try to bridge it out

 

[racerone]

Remove flywheel and see where the wires go.-----Ohm those wires.------Is the cutout switch there and working properly ?

 

[motorstuff]

tblshur: I tried at the black and striped black wires that would usually go to both M ports on the ignition switch.

 

[motorstuff]

racerone: How can I test the cutout switch? I’m not exactly sure how its supposed to operate.

 

[tblshur]

the print showes a black/white wire coming out of the points and it has a connector in it the connector may be disconnected or bad :joyous:

 

[motorstuff]

tblshur: Good thought. Just tested that wire/connector and getting good continuity.

On another note, should I be getting continuity between the two posts of the vacuum switch?

 

[tblshur]

try grounding the connector see if it shuts motor off

 

[tblshur]

with motor running key off ground the black wires on the cutoff switch if it shuts off cutoff switch or safety switch bad my guess

 

[F_R]

Y'all are barking up the wrong tree. The vacuum cut-out switch has nothing to do with shutting the motor off..

There are two black wires coming out from under the flywheel. CONNECT those two black wires together. The motor should shut off. If not, there is something wrong with the wires or their connections under the flywheel.

But if the above test does shut it off, the problem is somewhere between there and the ignition switch, or the ignition switch itself.

 

[motorstuff]

F_R thats what I was looking for. When I connect those two wires it dies. So there must be an issue with the wiring downstream then. Thank you!

 

[tootallofwa]

If you ground either/both black wires that are coming from the positive side of the coils/points the motor dies. Grounding can be accomplished by connecting them together since one set of points is always closed and grounded.

One of these point wires is connected to the center terminal of the cutout switch and then through the harness to a M terminal of the ignition switch. the other is connected to the other M terminal of the ignition switch through the harness. M terminals are connected to each other through the ignition swith internaly when the key is off thus grounding the points.

The cutout switch works with vaccume, too much (overrun) and it physically connects the center terminal to the block and kills the motor by connecting the points to ground. If there is cotinuity between center terminal and the block the cutout is bad. The outer terminal is a isolated terminal to bridge between the Safety SW and a start lug on the starter solonoid, which grounds the solenoid terminal when throttle is too far open to be in neutral and thereby keeping the starter from cranking in gear.

Also some engines temp sensor in the head that connects to the center terminal of the cutout to kill/connect points to ground in a over hot situation.

No Battery? No Ignition sw? no harness? Dont worry the engine doesn't net them to run. Manually Pull to start. Connect point wires seperatly to momentary type Kill switch, that connects them when pressed, to kill engine.

 

[oldboat1]

Try cleaning up the key switch. Use electrical cleaner in the key slot and operate the key switch a few times. Make sure the wire connections a bright on the back of the switch.

 

[F_R]

Go to the key switch and do the same test you did at the motor--that is connect the two black wires together. If it turns off, the wires between there and the motor are OK and you have a bad key switch (or connected wrong).

If it does NOT turn off by connecting the black wires together, there is a problem somewhere between there and the motor.

It's so simple.

 

[tblshur]

post # 9

 

[F_R]

Post #9 is suggesting cutoff switch or safety switch. That's the wrong tree.

 

[tootallofwa]

cut out switch has nothing to do with stopping the engine except in runaway which only happens with a spun prop, too lean oil/fuel, broken driveshaft(rare), No-Load condition. except that is where one of your coil/points wires mount. ground center post to kill the engine.