Kill/Saftey Switch Install on 1987 Merc 25HP

Hi Folks,


I have a couple of questions on a wiring project on a 1987 Merc 25HP. For a few reasons, I am maintaining the remote steering and remote throttle controls, but I am looking to disconnect the remote start. I have disconnected the remote start cable (the multi pronged plug) from the console. I am now looking to do two things:


**For ease of explaining, please see the attached photo of the switchbox in which I have identified the wires with numbers.


1 - Install a kill/safety switch. I have receievd this part and I am looking for the correct way to wire it into my switchbox. I will (somehow) mount this switch so it is accessible from outside the cowl and connect the lanyard there. I'm thinking I need to disconnect the black/yellow wire (Wire #3) that is currently wired into the disconnected remote start cable, and replace that with the black/yellow cable that is attached to the new kill switch, and then ground the black wire from the new switch to the engine block. I'm assuming that is what is happening at the console, but if someone could take a look at the diagram and verify that would be appreciated.


2 - Figure out why my engine will start with the remote throttle in gear. It is not required to be in neutral, and I do not need the "throttle advance" button pushed in to start it. Can someone explain how this safety feature is supposed to work. I'm assuming it has something to do with the fact that the remote start cable is disconnected, but I'd like to understand how to wire it so it is working again and prevent the boat starting in gear with the prop engaged.


Graham was nice enough to send me a switchbox diagram that was really helpful but I'm just not sure which of the two black/yellow wires I should be working with and with the cost of these parts I'm being extra careful not to damage anything.


Bonus question - If my assumption in #1 above is correct and I should be replacing the current wire to the remote starter cable, can someone tell me why it is working at all now? Is it becasue that black/yellow wire is not currently connected to a ground (it just terminates in the unplugged cable) and therefore presents resistance to the electricity, so it travels elsewhere (i.e. over the spark plug gaps)? I think Graham asnwered this for me in a different question and context but sometimes I need to state a question differently so I'll fully understand it.

Thanks as always for any assistance you can provide.
Rob

You have your question #1 figured out correctly. That third wire (blk/yellow) is the kill circuit wire. You can tap into that (if you want to leave the plug connector alone) and as you suspect, just wire that over to your kill switch and then ground the kill switch.

The neutral safety feature on these is located as part of the recoil starter (rope start). It's simply a plastic (finger) that locks into the flywheel so you can't pull it over by hand if it's in gear.

As far as I remember, your control for the electric start should have had a neutral safety feature (kills the ignition instead of locking the flywheel) to prevent a start in gear. If the control was changed at some point over the years for a different model then that feature could be lacking (or it's broken and was jury rigged/bypassed whatever)

And the your bonus question The reason why the kill circuit is not preventing the motor from running now is because it does not terminate to ground anywhere at the moment. Since nothing is plugged into the (plug) that black/yellow wire is just kinda hangin' in space. The power from the ignition is looking for a way to get to ground, which in this case is by jumping the gap on the sparkplug...

Thanks Graham! On #2 that probably explains why I wasn't getting any spark when I had the remote start cable plugged in with no key or battery (maybe??). Do you think there is any way that this feature on the flywheel itself could be missing? or never in place. I don't see anything like what you are describing, although I haven't removed the flywheel to look underneath. I'd feel better with a mechanical device that stops the flywheel when not in neutral than a wiring solution that cuts the spark.

So for the "locking the flywheel" method, it would need to be somewhere connected to the throttle linkage correct? So it would know when to engage?

Thanks as always, I'm learning a ton taking this motor apart but I'd be lost without all the assistance here.
Rob

Here's a couple of diagrams that show where it should be, how it works etc.

Thanks Graham, Found the problem from that diagram. Check this out:



The "Lever, Lock (Upper)" as described in this parts diagram (Part #3 below) has been snapped off and there is nothing to prevent the pull of the cord. I'll order the part and replace and that should solve the issue.

Any advice for getting the little pin (Part #7 "Roll Rin Lock Lever) out of the lower part so I can remove and replace the broken piece? I also included a picture of the side view of the pin. It looks like it has a split in it. It might just push out but I don't want to force it.

Thanks Again!
Rob

I started down this path because I bought the boat and motor and there was no key and no battery. The steering and throttle work great so my plan is to make sure the motor is running well itself. Then if all is well, I'll turn my attention to the remote start, get a key and a battery and see if I can get this going. But honestly I don't mind just using the starter rope as long as everything is SAFE.. That's why I want the lanyard from the engine. I realize that if I get the remote start working I will have a lanyard connection from the console, but I'm doing this as a short-term solution, possibly. I may decide to just leave it this way.

In either case making sure the flywheel lock works is critical with or without the remote start. I got a good deal on the switch, so it's not a big investment.

Rob

Thanks. You had actually given me that info last week in a different thread. I didn't want to complicate the story in progress, but the previous owner called me last weekend and told me he found the key and he is sending it to me. So that was good news. So I still need a battery and I haven't looked at any of the cabling inside the small console (I think that is where the battery would go). This is just an 11' Del Quay (British Version of the Whaler), so there isn't much room for it anywhere else. Besides I assume the cables all terminate there. Maybe I should just go for the remote start after all I'm in Boston so I'm running out of time to play with it before I need to wrap it up for the winter.

What type of battery would I need for just the starter? What size? etc?

Thank you for pointing out that it will still start in gear, just not beyond an idle. I'm sure I would have driven myself crazy trying to get it to not start at all in gear.

Rob