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How to Troubleshoot an Outboard Kill Switch

In this video we take a look inside an outboard kill switch. Knowing how a boat safety lanyard and cutoff switch works can be really useful installing or troubleshooting an outboard kill switch.

Dangar Marine

About Dangar Marine

MarineEngine.com proudly sponsors the Dangar Marine YouTube Channel. Our friend Dangar Stu draws on his experience as a commercial boat skipper and mechanic to make some great how-to videos. Dangar Marine videos cover a range of relevant topics in outboard repair, boat repair/upgrades and seamanship. Subscribe on YouTube to be notified when new videos are released.

How to Troubleshoot an Outboard Kill Switch – Video Transcript

Hey there, Dangar Stu here. Today's video is on lanyard kill switches and is proudly sponsored by MarineEngine.com.

Today's video is the first video that MarineEngine.com has sponsored so big thanks to those guys for getting on board and helping out with the channel. For those of you who don't know, MarineEngine.com sell all sorts of parts for outboards, so if you're doing repairs or maintenance of items, that sort of stuff they sell. So if you're looking to replace a kill switch like this they're the perfect people to grab it from.

What I'm going to do today is just show you what's inside these. They really are just a switch there's nothing special about them but they have been getting quite a few questions about them lately so I thought it's a good time to go through how they work. This particular kill switch is from a Yamaha outboard. but they're identical in principle on across all outboard brands. The way these ignition system work more or less is that you have a magnet on the flywheel so as you start the outboard by using the pull start or turning the starter motor the flywheel starts to spin as a magnet in the flywheel passed into this pulser coil the magnet induces our current into that coil so a small current flows through the coil and comes in here into the cdi.

Because the flywheel is keyed on to the crankshaft that happens at a very specific point in the cycle so it knows which Piston is on the compression stroke which Piston is on its you know exhaust stroke etc. and it uses that information to know which spark plugs to fire. Here I have drawn a pretty simple setup which is a two cylinder motor that shares a single coil. so it gets a signal from the CDI to fire when it gets that signal both spark plugs fire simultaneously this particular system is called a waste spark system, because only one of the Pistons will actually be on a compression stroke in the sparks fire so the one that's on the compression stroke will actually fire it's got fuel in there and it will fire. the other one won't be on that stroke it'll just essentially be a waste of spark so that's why they call this particular system a waste spark ignitions system.

The system works that way if the lanyard is in, and what happens when you put the lanyard in is you're taking a switch like this that currently has this white wire connected to the black wire and you're pulling the screw away from it that's what this little lanyard does it pulls that switch out and it disconnects those two wires for each other. With them disconnected, all the current flows to the coil the spark happens. If you pull the lanyard out, then this switch becomes on and what that does is send the current and stares down this white wire through your switch in turn ground the spark stopped and the engine cuts out so that kind of answers I guess one of the most common questions is how does this work just turning it on turn the motor off or just turning it off turn the motor off and the answer is that turning this switch on turns the motor off if you would have cut this wire the motor would keep running on the Yamaha motors, this kill switch wire is a white one and on you sort of Mercurys and Evinrudes it's a black and yellow wire that wire comes out of the CDI unit.

These CDI units come in all different shapes and sizes and in this case these are two Yamaha ones and so here's the white wire one here's the white wire together so I know these are the two wires the go off to the kill switch. these switches can fail in a couple different ways one is that they're permanently closed in which case you will never get spark and you won't be able to start the motor you'll be all starting or turn the key and you'll never get spark because it's always going to be sending that spark energy to ground the other way is that this is never going to close in which case you won't better switch the motor off the motor we running you'll pull the lanyard out and the motor will keep running. I've got a kill switch over on the bench at the moment which is broken in the open position the motor could never be turned on so I'll show you that then we'll pull one of these apart and see how it works. The switch on the outboard I was looking at when this problem sort of came up looks like this it's one of the sort of rubber backed one so you can press it so I'll just cut this off and I'll show you what you see inside is just two contacts and without the whole top part of this switch there's no way for those contacts to be connected and for this motor be turned off so this is an example of a switch that would just run on pull the switch out well the whole thing's gone.

You know so without manually grounding it out the motor will just run on forever. this is another older switch that's off another outboard, but I'll open this one and show you what presuming is actually a working mechanism. you can see here that this switch has a flat on the top part of the casing and on the bottom so I'm just going to put a couple of spatters or a shifter and a spanner onto this and we'll open it up. the shifter I'm going to put them a large side and the other sides are 19 millimeter. so what you can see here you've got, and I'll take this apart further is a little plunger section so as you pull on here this plunger retracts, there's a little rubber seal under here is a conductive disc and then here are your two connectors so whenever the switch is screwed together and they lanyard's out that little plunge is pushing that conductive disc onto the two terminals the switch is in the on position which means that the ignition is grounded and the motor won't run. on the tip of the plunger there is a little circlip so I'm just going to go get that pick and pull that circlip off. People also often ask about these little picks I find them really useful I use them a lot they I think that sold as o-ring picks so that's what I'd sort of search for.

If you look into buy one this seems to be the most common type which has a hook on one end and then this sort of spiral section like that that I must admit is actually quite good for sort of hooking an o-ring out but I also really like this straight one straight like that with just a ninety degree I find that really sort of versatile as well so in this case I'm just going to use it to hook this little circlip out, just getting in here and levering it away. could not predict that could you. Now I'm going to go find the bits. When you're doing this I highly recommend you don't do it sort of pointing it towards a camera, you're much more likely to lose bits so what we've got is a washer that was at the end of that plunger and then the spring that was pushing it forward if that spring has failed the effect it'll have is that you put your lanyard in and your motor will start just fine, but when you pull that lanyard out the switch will stay out so the motor won't cut off what you would have to do then is push the button in manually which would then ground the ignition the motor would go out. so if that's not happening automatically it means that Spring has failed. The plunger section of this casing really is this plunger the spring that goes on the washer that goes on and the little circlip that holds the washer on in the other section. Should this little conductive disc be so corroded that it's not going to conduct electricity, then you'll find that the kill switch won't function properly and you won't be able to switch the motor off.

It's probably most common just to replace these switches they do have individual components if they're not available separately your might be able to improvise. I mean this is just a disc of metal this is just a spring find something in the ballpark chances are you'll be back in action. Other common things are just bad connections that white wire or the black and yellow wire if that's got a bad connection then the motor you know won't cut out if the ground connection onto the engine block is not good the motor won't cut out. another situation which I've had I think I mentioned in a previous video with the soggy Johnson tip thing, was that often these wires often one connector and if that wire has water in it then electricity without a flow from that white wire or the black and yellow to ground even though the switch is in the off position which is the engine being in the on position when that happens you'll either get a no spark or a weak spark because most of the currents flowing through the water to ground so if ever that white or black and yellow wire has a path to ground then the motors not going to get spark so if you've got no spark that's a really good first place to look. Sometimes these switches are really easy to replace in this case where it's one like this it's just a couple of short wires and some bullet connectors nice and easy.

Other times with some tiller switches they actually get fed right through the tiller and the can be a little bit hassley. At the end of the day though it still is only a 2 wire connection so they're pretty straightforward to replace yourself. All right we'll wrap this sort of video on kill switches up with a bit of a practical demonstration of how they work and don't work of course the outboard I plan to use demonstration now isn't starting. It's been sitting in the workshop for ages and hasn't been started, hardly surprised. when I prime the bulb it just starts to overflow from the carburetors so the needle and seat wasn't closing. I took the cover it off and you can see here that the floats just completely stuck open so it's no surprise was free flowing. so I'm going to take it apart give it a clean put back together. yeah so just taking the screw up now the float pivoting nicely but even here I feel I can't took quite a bit of force to pull the needle out of the seat so obviously it's just a bit gummed up in there. So that's the needle that's what they look like I'll give that a little clean. this little bit here is the seat that the needle goes in to shut the fuel off so I'll put some carb cleaners and compressed air will clean it up I'll blow the jet out over here and we'll try again so I'm just going to blow it out.

One thing you can see is if I put carb cleaner in here you can see it comes out here and goes up my elbow, but that's the path the fuel takes. comes in through here from here into the bowl that's the cover the bowl so now I've put a bit of carb cleaner in there I'll let it soak for a little bit in a compressed air and then I'll just manually put the needle in and see how it goes it feels good we'll put back together but if it still filter is sticking I'll do some more cleaning. the needle feels much more free in the seat now so I'll put it back together and we'll see if we can prime it without it overflowing. we'll just clean out the bowl before I put it back. Obviously it's this gunk and this evaporated two-stroke oil which is the fuel that's left the oil behind that's gums it up. Right, if I pull the kill switch out on this now, it will stop as normal. I've put the kill switch back in now and these are the two wires here coming from the kill switch white one to the CDI unit the black ones just going to the engine the engine block as ground, what I'll do now is just disconnect the white wire start it up, then ill pull the kill switch out. you'll see it won't stop because even though the kill switch is not active the currents coming through this wire and its never going through to the ground.

The last thing I'll show you before I go inside out of the rain is I'll disconnect the kill switch again and I'll grab a piece of wire will started and show you how I can stop it by taking that white wire from the CDI unit and then just touch it to the engine block which is ground. What we have here is a piece of wire ordinary piece of wire, nothing inside it nothing behind it. This is the wire from the CDI and ill just touch it to the engine block, and that's essentially all the kill switch does, is take that wire put its ground.

Well thanks watching a huge thanks to MarineEngine.com for choosing to sponsor the channel it's certainly going to help me make plenty more videos down the track so that's much appreciated. I really hope you guys check out their website they sell loads of parts for outboards. so all the jobs I've been doing videos on if you're looking for the parts you need to complete the job they're definitely guys to go to. Alright we'll take care I won't tell you what I'm going to do next week because every time I do it's wrong. So we'll see. Still have the painting to do still got the Evinrude to finish. We'll get there all right, see you guys, bye.