Can't kill engine

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user 7806

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I have a 1971 Mercury 200 20 HP with electric start. When I looked at the boat and motor last week and were running it with ear muffs you could turn the key to off and the motor would die.

2 days later when it was taken to the lake for atest drive then only way to kill it is to idle it way down. The previous owner would unplug the electric cord when not using the motor, why I can't day I think because that is the way his dad did it, before I start tearing the switch out to see if there is an issue with the switch is it possible that the plug isn't all the way in? Seems to me it didn't go in to far. Haven't had chance to test this out so I thought I would ask here.

If it's not the plug is there anything else ovious that I should be looking at before running the wires down for issues?
 
Does the kill button on the motor not work either? It should work even if the plug is disconnected. If it's not working then I would look at where the wires from the points tie in to the wires from the kill button. According to the wiring schematic I have, that is the connection point in the wiring that the kill button on the motor and the key switch have in common.
 
I'm have to look I haven't seen a kill button on the motor itself, I need to find where it's located, I don't recall seeing one.
 
Usually not hard to spot...either at the end of the throttle arm...like a button right on the end...or on the face of the motor staring right atcha...it should have one for sure.
 
JMichael said:
I've got the same motor except it's a 75 model. Look just forward of the shift lever on the bottom edge of the cowling.

JMichael thanks for the tip. Sure enough there is a BIG black button by the shifter so I will assume that it's the kill switch/button. To windy today to take the boat out and try it.

Now why the key switch no longer works, I know it did when I was looking at the boat and we were running it with muffs, strange.

The previous owner would unplug the cable to the motor each time when finished using the boat. I don't see the purpose in this, the battery is disconnected so there would be no power going to the motor anyway. Am I missing something or is it okay to just leave it plugged it?
 
Unless someone has done something strange with a rewiring job, that's the kill button. When I got my motor, the contacts inside the kill button were very dirty and tarnished. I took it apart and cleaned them real good and it works great now. I never unplugged my harness from the engine. It seems to me that it would just expose the pins in the connectors to dirt and the elements.
 
I think I might need to clean mine too. It didn't work. I did make sure the plug was plugged in all the way and for the most part the key would kill it sometimes. I think I might have a loose connection soomeplace.

Does you Merc 200 charge the battery when it's running? I thought mine was suppose to but I check it today with a volt meter and it only show 12.75v which is about what is shows with nothing on it.

The pins on my motor plug look a little dull, maybe I need to get some contact cleaner and clean them up some. Before it wasn't pushed on all the way as I could still see the spring on the motor side. I had to bang it on with a rubber mallot after spraying a little lube on it.
 
No, mine doesn't have a rectifier on it so it can't charge the battery. The places I normally fish, I don't ever run the motor long enough to charge the battery any ways, so it's not worth it to me to buy the parts needed so that it would charge the battery.
 
I was just a little better than an idle when I checked mine today. When I was at Harbor Frieght tonight they had a automotive volt meter for $7.99 so I picked one up. That will at least give me a good idea as to battery condition. Right now I only have one battery so we'll see how that goes.

Thanks for all the help with my Merc 200, I searched for an owners manual on it online but so far haven't found one.
 
A meter is not really useful for testing your battery. It only shows voltage and even a bad battery can give a reading of 12+ volts. You need a hydrometer and/or a load tester. While the average person isn't going to own a load tester, a hydrometer is very affordable at $5-$10.

Owners manual or service manual? I've been trying to find a factory service manual for mine. I've got a Sealoc manual but they try to cover too many different motors in one book so they don't cover all the details on your specific motor. It's better than nothing but not by much.
 
JMichael said:
A meter is not really useful for testing your battery. It only shows voltage and even a bad battery can give a reading of 12+ volts. You need a hydrometer and/or a load tester. While the average person isn't going to own a load tester, a hydrometer is very affordable at $5-$10.
I proably have a hydrometer out in the garage if the bulb isn't hard as a rock. I wasn't putting a voltmeter in for testing just for showing the battery voltage and if it does charge it will show like 14 volts. I like the volt meter better than an amp meter and is much easier to wire.

Owners manual or service manual? I've been trying to find a factory service manual for mine. I've got a Sealoc manual but they try to cover too many different motors in one book so they don't cover all the details on your specific motor. It's better than nothing but not by much.

I bought a manual online the other day that covered from 9-40 hp 2 cycle Merc & Mairner engines. It was only $5 and is a pdf file, it's better than nothing. I found a factory service manual online off a link I found in a forum somewhere but it was $99 as I recall and was suspose to be a reprint of the actual Mercury Service Manual. Don't remember what I found it and I can't find it again now. I hate ti when that happens.
 
When I tried the black button by the shifter the other day it wouldn't kill the engine. So today I decided to take it out and clean the contacts. To my surprise there was no wire on it. Well there was but it was only about 1/2' long and didn't got anyware. There was not sign of it over on the other side where the block is according to the wiring diagram. I ran a wire over to the block on the other side and attched it to the lug with the salmon wire. So next time out well see if the button now works.

The one wiring diagram I have which says 1972 on it show the kill button disconnected if an electric start option is installed. You cut the wire at the switch and connect it to a junction block which has a Salmon wire from the sator and from the key switch.

Mer200wiredia.jpg
 
Gramps50 said:
When I tried the black button by the shifter the other day it wouldn't kill the engine. So today I decided to take it out and clean the contacts. To my surprise there was no wire on it. Well there was but it was only about 1/2' long and didn't got anyware. There was not sign of it over on the other side where the block is according to the wiring diagram. I ran a wire over to the block on the other side and attched it to the lug with the salmon wire. So next time out well see if the button now works.

The one wiring diagram I have which says 1972 on it show the kill button disconnected if an electric start option is installed. You cut the wire at the switch and connect it to a junction block which has a Salmon wire from the sator and from the key switch.


Different wiring all together since it's for a 72. The 72 had breakerless ignition if I'm not mistaken and that schematic looks totally different than the one I have for a 71. Of course this sealoc manual could be wrong. LoL
 
I have another one that show a points type engine and the wiring in mine looks more like the diagram that I posted. Mine has the 2 seperate coils like the picture. I also saw Thunderbolt on it somewhere if I remember correctly.
 
I was just going by the title, these are not computerized here so there could be a mistake. Will the serial number tell for sure?
 
According to what I have looked up it's a 1971 SN# 2991932

In the search I found the service manual, or at least I think do https://www.maxrules.com/fixmercmanuals.html looks a little pricey to me but with the cost of repairs it might pay for itself.

Here's a parts manual might be worth the $5.95 to have https://store.oldmercs.com/category_s/1618.htm

Ordered the parts manual and downloaded it, looks like it will be a handy reference, has all the part numbers with eploded view of the components with numbers to the parts.

This place had the factory service manuals for $75 https://www.eastcoastmarineservice.com/models.html
 
It does show that to be a 71 serial number but it's possible the clamp was replaced at some point and could be showing the wrong serial now. Does your engine have an ignition module mounted to the right side of the engine? It might have a front cover off of a later motor also. That would explain it saying Thunderbolt ignition on it.
 

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