We have had some strange behavior from our Yanmar diesel engine: it would refuse to shutdown sometimes. Then, this year, it refused to start as well. Nothing that couldn't be circumvented with a screwdriver so an electrical problem that I diagnosed as a short in the wiring harness. Puzzling as it looks good but stranger things have happened, so one of my projects on the list was to pull two new wires from the control panel to the engine, for the start- and stop-signals.
Before we got to that item on the list, we have been working on removing old and/or unwanted systems. I have a weird type of minimalist preference where I remove many systems that are just not needed but the systems I have must be the best available :) In this case, we have removed an automatic fire suppression system that we had in our engine room. It was halon based which I find scary (I had that in the datacenter of my company and had nightmares about employees suffocating etc.) plus we feel that it is not needed with a diesel engine. We of-course have good manual fire extinguishers.
After removing the scary bottle with Halon gas, we removed automatic and manual activators and that left an electric box and a little panel at the steering wheels. We removed that and followed the wiring all the way inside the boat... to the engine control panel... WTF ! This was when bells started ringing in my head: this fire suppression system was able to stop the engine as well as prevent it from starting, which were the exact symptoms we still had to deal with further down our list.
This morning the weather was too wet for epoxy work so I removed the engine control panel, then traced and disconnected the 4 wires from the fire suppression system and the engine works like a charm again :)
As there's no pictures with this post, I just picked a random one from us living in Paradise: