2016 Mercury 115 2.1l earthing grounding shorting issue

[QBhoy]

Hi
Tracking down an earthing issue and obviously done the usual things
Wondering if either the ground cable that travels down the mid section to gearbox and also grounds the trim pump is the issue or perhaps the other suspect is the ignition or kill switch. Are the remote throttle boxes known to have issues from moisture perhaps ? Every single item on the boat is buzzing and audible. The engine is being affected by it too.
Also perhaps wondering if the FSM and its lp lift pump might be failing and overheating…causing a huge draw on power.
Thing is that the voltage fluctuates between 14 and 15v when it happens and sits at 14.5 when in between shorting. Lots of troubleshooting to do with the meter this weekend but perhaps looking for known issues
Thanks.

 

[Faztbullet]

Post is confusing...what exactly is happening?

 

[QBhoy]

Post is confusing...what exactly is happening?

Apologies. Just wondering if there are any known issue with the modern mercury like this, that would cause electrical issues that show sporadic voltage fluctuations between 14.3-15v. Also enough to result in the engine running poorly from not getting enough power to run its ignition system. The power trim toggled will result in a huge voltage drop and bog in engine rpm. More than the expected. Static all round the electric system and shorting suspected. It’s not the usual suspects like battery, it’s terminals etc. I suspect it’s either to do with the trim motor shorting or it’s switches or the ignition barrel or kill switch wiring perhaps.
This is very random when it happens but much worsened if the trim is used. If I cycle the trim tilt down to up and back down..it can either better or much worsen the effect once the engine is started again. If I flick the trim switch or remote control box even a little..it can worsen or better. If I touch the wiring harness to the control. The same. If I touch the main wiring loom harness into the engine, the same.
I’ve disconnected all the sensors and control plugs and no different. Disconnected the remote harness plug and no different either. With this unplugged the trim still works.
I’m going through the manual now and hopefully doing more testing tomorrow. It’s not the rectifier or associated for sure. Not the plug leads or coils. Neutral safety switch may be suspect perhaps.

 

[Faztbullet]

Stator....

 

[QBhoy]

Stator....

Narrowed it down to the remotes and or cable run between there and engine. Had it temporarily fixed today after taking the remotes to bits. Throttle operation went to as easy and smooth as it’s ever been. Ram perfect for an hour then went stiff again and problems started again. Not as bad though. Getting there b

 

[QBhoy]

Update. Removed the remotes again today and re seated the cables. Runs well again but gets stiff gradually and shorting/earthing/switching starts to creep in. Definitely to do with the cable run binding and perhaps making a worn wire insulation allow shorting..or the tightnesses either resulting in mechanism contacting the neutral switch or kill switch wiring being pulled on by loom (that’s getting jammed between the cables)…
Boat is coming out on its trailer for a proper look. Keep you updated.