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96 Johnson 60hp melted wiring insulation

B

blue swan

New member
Hey guys

Ive been having some problems with my 60 Johnson ex VRO lately.

the 1st issue was intermittent slow mode which I finally solved by tracing the wires for the temp sensor only to discover the brown wire exposed from melted insulation and earthing on the block. I suspect intermittently hence intermittent and erratic slow mode (drastically drop to 2500 then hunt back up to wot then back down again)

after repairing with heat shrink I have had 10 amazing trouble free trips running like a champ. In the process of attempting to fix the intermittent slow/hunting issue I replaced all 3 coils, leads and spark plugs. As well as brand new plastic tank. Every gas line replaced from tank to carbs. New bulb and rebuilt carbs with OMC kit and set float levels. New water separating filter and new inline engine filter.

last trip I started to come home from out in the bay when half way back I got this erratic miss. I stopped to swap tanks to find I had 1/8 of a tank left? I still swapped tanks anyway but the miss was still there. It gradually got worse until the motor died suddenly. After an hour of attempted re start I got a tow back to the dock.

when I got home I managed to get it to start monentarily but it would die 2 seconds later. I found out of the two big black rubber power pack connectors, the one on the right with 5 wires (2 brown, 2 orange and a black) that smoke was coming from it. I pulled it apart and found it had melted slightly and the wires inside must have been making contact or arcing. I re pinned the connectors with spare plugs off an old faulty spare power pack. Reconnected everything and she fired right up and ran perfectly on the muffs.

my question is this a freak thing and will I be sweet now or is something more sinister lurking and will this happen again?

cheers guys
Josh
 
Have you looked into an updated water pump kit, yes or no.----Replaces thermostat parts and uses a six vane impeller.-----Might do a compression test on it as well.
 
I'm sort of in agreement with "Racerone" IF when you turn the key to the ON position, the warning horn fails to give its momentarily test beep sound.... that is, either the engine is overheating and the warning horn is either missing or faulty as the warning horn should sound steady and constant when the engine approaches the overheating point.

If the warning horn system is working normally and the engine is not overheating... then you have one hellava wiring problem somewhere.
 
Racerone I have not looked at an updated kit. As far as I'm aware the impeller was done in the last two years and the tell tale comes from the top of the block not the bottom which was a change that had to be done on some of these motors i believe. Ether way the motor has never been to hot to put hand on the flywheel after shutting off and always has a strong stream.

compression has been tested 3 times in 6 months always comes back 130 across all 3

joereeves the warning beep sounds when the key is turned on and also I have done the test where you earth the temp sensor and the alarm sounded correctly as well as touching VRO wires together it sounds so as far as I can tell the warning system is functioning correctly.

could I be getting to much voltage from stator or rectifier if that's even possible?
 
The tell tale on yours came from the factory at the top of the block !---------A strong tell tale does not mean that motor is cooling properly.
 
blue swan said:
I found out of the two big black rubber power pack connectors, the one on the right with 5 wires (2 brown, 2 orange and a black) that smoke was coming from it. I pulled it apart and found it had melted slightly and the wires inside must have been making contact or arcing. I re pinned the connectors with spare plugs off an old faulty spare power pack. Reconnected everything and she fired right up and ran perfectly on the muffs.
Click to expand...

This (above) partial quote from your post #1..... What about the rest of the wiring on the power-head? If the engine overheated to a point whereas it caused those plugs to melt in the manner you describe, "ALL" of the wiring should have been affected, the warning horn should have sounded, and the engine rpms should have died down gradually as the pistons seized to the cylinder walls.

If you've had this engine for some time and it has run properly in the past..... has anything been done to this rig recently? Something installed, repaired, whatever? A friend with "expert knowledge" lending a uninvited working hand, that sort of thing.

It sounds like, somehow, battery voltage is being supplied to that ignition system which will, in fact, destroy it. If the internal workings of the ignition switch has failed whereas battery voltage could be applied to that black/yellow wire (kill circuit) that's attached to the "M" terminal... that would do it.

That type ignition, "Magneto Capacitance Discharge" ignition has been the standard since 1973 and I have never heard of such type a failure.
 
Joe the only other damaged wiring was repaired by myself a few months back which was the temp sensor wires and I slid some heat shrink up the wire and warmed it onto them. I've had the boat and motor 3 years and I've only ever worked on it in that time.

some of the wiring on the motor has a similar problem to what I found with the temp sensor which is the insulation has a "jelly" type feeling in sections and has gone a bit soft I put this down to age and have done similar repairs by sliding heat shrink over it to ensure it doesn't split and arc on the head.

the more I ponder different scenarios is it possible that the pins inside weren't making good enough contact and arcing, creating the heat required to melt the inside insulation away. In turn making the arcing worse and then arcing between pins causing the misfire? The reason I suggest this is during my first issue of "slow" mode I swapped the power pack over a couple times to ensure it wasn't the culprit and potentially pulled the pins too far back into the rubber Connector
 
I don't know if the "pin/socket" scenario you speak of could result in the problem you've encountered... BUT... many times I have encountered the pin/socket separation (backing out) scenario that has resulted in ignition problems... worth a look see.
 
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