1971 Mercury 4hp 2 stroke Merc 40
- Thread starter Scott O.
- Start date
Ground out the spark plug wire with your finger.
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First time I've heard of something like this. I'd suggest looking up the parts diagram on line to see if someone has removed the kill switch and it is just missing. I suspect one could rig up a kill switch easy enough if the parts are not available.
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First time I've heard of something like this. I'd suggest looking up the parts diagram on line to see if someone has removed the kill switch and it is just missing. I suspect one could rig up a kill switch easy enough if the parts are not available.
Tom Scholberg
Well-known member
I have a hunch that there is a kill switch that makes contact when you close the throttle. Just a WAG (wild --- guess). I'll sniff around in some books here and see if I can nail it down. Take care of that back.
Scot
I looked it up, there is/should be a stop switch assembly which runs thru the inside of the tiller handle. Try pressing firmly on the end cap of the tiller handle. You will have to hold it pushed in until the engine quits. It is a momentary switch as soon as you release the switch, the engine will begin to run again if it is still spinning. I never did like that style, just for that reason.
I looked it up, there is/should be a stop switch assembly which runs thru the inside of the tiller handle. Try pressing firmly on the end cap of the tiller handle. You will have to hold it pushed in until the engine quits. It is a momentary switch as soon as you release the switch, the engine will begin to run again if it is still spinning. I never did like that style, just for that reason.
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Scott O.
Well-known member
The mystery continues...no kill switch in the tiller handle end.
Tom, I figured the same thing...twist throttle to full off but that didn't do it.
I have looked everywhere online for the user manual but it's 45 years old. If anyone has any ideas, it's a Mercury (model 40) (1 CYL.) Mercury Outboard
I kind of liked Tod's idea
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Did you look up the exploded parts drawings? parts catalog The drawings will show you what you need as far as the stop switch is concerned. Appears to be two contacts on the end of the switch assembly. You may have to disassemble everything and do a clean up of all pieces? or trace the wire down and add an external switch some where on the engine housing.
View attachment stop switch2.jpg
View attachment stop switch2.jpg
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Gordon Bartlett
Member
The operator's manual is available online as a PDF file. The single cylinder models (40 and 39) don't have a kill switch. It says shift into neutral and choke it.
CK Jackson
Member
That does bring back memories-- while I didn't run Mercs, I do remember that often enough on old kicker motors, using the choke was one way of killing the motor.
However, usually we would pull the gas line and run the fuel out on the last drift of the day. That seemed to save the carburetor. It made the it easier to start the nest day.
However, usually we would pull the gas line and run the fuel out on the last drift of the day. That seemed to save the carburetor. It made the it easier to start the nest day.
That is interesting, the only listing on Mercury's web site for a 40, shows the 40 model as a two cylinder and that is the illustration I have shown above. Detail 7A is listed as part #70671A1 Harness Assembly Stop Switch but is no longer available.
Scott O.
Well-known member
This corroborates the info I have found. I just found info stating that the kill switch was an option from '72 until '76 when it was permanently added to the design. Thanks for the help on this...Daves diagram gives me a head start if I get ambitious enough to add my own kill switch
Phil Eager
Well-known member
With all the safety laws today its amazing that any of have survived to live as long as we have.
Gordon Bartlett
Member
Actually, those little motors are fine without a stop switch. Throttled down, and with the choke closed, they stop dependably. I've never heard of one running on. OMC used a different approach on their 4hp and smaller motors of that era. On those motors the speed control lever controls the ignition timing plate as well as the carburetor. Moving the speed control lever to the "stop" position not only closes the throttle, it also retards the timing so ridiculously late the motor can't run. Works every time. I did add a kill switch to one of mine, though, just so I can use a lanyard clipped to my jacket so the motor will stop if I fall out of the boat when I'm hunting alone.
Gordon Bartlett
Member
Scott,
I used something similar to this:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=4800&familyName=Sea-Dog+Universal+Ignition+Kill+Switch
but I’m not sure that’s what you are looking for. This is an emergency kill switch. This type of switch is always “trying” to stop the motor. The only thing keeping it from stopping the motor is the little clip holding the button. When the clip is pulled off the button, the switch closes, grounding the ignition wire, thereby stopping the motor.
If you want an ordinary stop button, you could use something like this:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=3475&familyName=2+Position+Push+Button+Switch+M608
With this type of momentary switch, the motor is always ready to run. To stop the motor, you just push the button in and hold it in until the motor has stopped.
But before you go installing a stop switch ... Your motor really shouldn’t keep running when the choke and throttle are both closed. Something is a little off. Maybe a tune-up is in order. If you do the tune-up yourself, get the service manual and follow it step by step. Those service manuals do a good job of organizing the process so all the bases are covered. Timing, fuel/air mix, and throttle/timing synchronization are all important. Of course, you’ll also want to make sure the choke plate is closing properly.
I used something similar to this:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=4800&familyName=Sea-Dog+Universal+Ignition+Kill+Switch
but I’m not sure that’s what you are looking for. This is an emergency kill switch. This type of switch is always “trying” to stop the motor. The only thing keeping it from stopping the motor is the little clip holding the button. When the clip is pulled off the button, the switch closes, grounding the ignition wire, thereby stopping the motor.
If you want an ordinary stop button, you could use something like this:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=3475&familyName=2+Position+Push+Button+Switch+M608
With this type of momentary switch, the motor is always ready to run. To stop the motor, you just push the button in and hold it in until the motor has stopped.
But before you go installing a stop switch ... Your motor really shouldn’t keep running when the choke and throttle are both closed. Something is a little off. Maybe a tune-up is in order. If you do the tune-up yourself, get the service manual and follow it step by step. Those service manuals do a good job of organizing the process so all the bases are covered. Timing, fuel/air mix, and throttle/timing synchronization are all important. Of course, you’ll also want to make sure the choke plate is closing properly.