Reply
 
Thread Tools Search this Thread
 
Old 02 July 2015, 09:10   #1
Member
 
Country: UK - England
Town: Northam
Boat name: My Boatty Too
Make: Honda
Length: 3m +
Engine: Ymaha 2.5 outboard
Join Date: Aug 2012
Posts: 15
MERCURY 50HP 50ELPTO 'Kill' wiring.

Hi again

Our Sea Cadet unit's boat cannot be put back on the water until the faulty safety kill switch is sorted - fair enough.

When I was tarting up the boat a few months back (sans engine) I had a look at the actual safety switch knowing, from last season, that the 'safety kill' had issues (it's a toggle type switch which you loop the kill cord over) and checked it with my test meter - it worked solidly, reliably and repeatedly. That's as far as I checked, tho', as we have a local repair shop for proper servicing and the actual engine wasn't on the boat.

Oookkkaaayyy, when that shop was carrying out a repair to the fuel pump recently, I went to have a looksee under the engine cowl to see how they were getting on (the boat is 'dry docked' at the moment) and found that a black/yellow wire had been cut inside a harness.

Ok, they have now 'fixed' the engine's fuel issue and a looksee under the cowl shows that they've re-crimped that cut wire. However, the top ignition coil still has it's black/yellow wire hanging loose - it's been cleanly cut and goes nowhere.

They have just told us the boat cannot go back on the water as the safety stop doesn't work properly.

A surf for wiring diagrams shows the 'black/yellow' to be the 'kill' wire...

A few questions, please;

1) Should all three 'black/yellows' (3-cylinder) be connected?
2) Would the engine be able to carry on running if only two were 'killed', even roughly?
3) Can you confirm for me (as I recall during my testing) that the kill switch works by killing the engine when it's 'ON' - ie. it 'shorts' the circuit and not 'opens' it?

Many thanks for any help on this.
__________________

__________________
Devs Ad is offline   Reply With Quote
Old 02 July 2015, 10:10   #2
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
3 cylinder trying to run on one cylinder? Not likely. Better if all were connected though.

I would guess that the switch, when activated, is taking a normally powered connection point and grounding it. That is a guess, though, and may be opposite on your motor. A bit of probing around while the motor is running should tell you which way it is (as could someone more familiar with your motor.)

jky
__________________

__________________
jyasaki is offline   Reply With Quote
Old 03 July 2015, 05:01   #3
Member
 
Country: UK - England
Town: Northam
Boat name: My Boatty Too
Make: Honda
Length: 3m +
Engine: Ymaha 2.5 outboard
Join Date: Aug 2012
Posts: 15
Thanks jyasaki.

Yes, I'm pretty sure that the kill switch works by grounding the ignition coil at some point, so it's a case of 'closing' the switch to kill the engine.

The repair guys are working on it now, so I'll be interested to see what the problem really is.

I don't have access to the wiring diagram inside the engine itself, only for the start/throttle control unit. Does anyone know if the black/yellow wire - which is grounded to safety-stop the engine - is simply connected to each cylinder's ignition coil's black/yellow wire in parallel, or is there another component of some sort involved?

Thanks.
__________________
Devs Ad is offline   Reply With Quote
Old 04 July 2015, 05:08   #4
Member
 
Country: UK - England
Town: Northam
Boat name: My Boatty Too
Make: Honda
Length: 3m +
Engine: Ymaha 2.5 outboard
Join Date: Aug 2012
Posts: 15
In case it's of info to others, I managed to find a service manual for the Mercury 40, 50, 55 and 60 Hp models:

Boatinfo - Mercury Service Manual for 40-50-60 hp

From this it's clear that all three black/yellows should simply be joined together and it's all grounded (we call it 'earthed' on this side of the pond) through the kill switch to cut the engine.

Seems there is a "fault in some component in the engine..." so I can only guess it's within one of the ignition coils itself.

Cheers.
__________________
Devs Ad is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 11:06.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.