I assume no generator since you have butane.
When you pull the stove I think it will be a pretty rough cut opening.
Trimming it would be some work.
But if you get a large thin cutting board you could place it on top and screw it from underneath.
If the concern is the module fails it can be bypassed easily.
There is a terminal strip on each side of the module with two wires for each device, port, starboard engines, generator and blowers.
All you need is a Phillips screwdriver and combine each pair onto a single screw. Take about five...
Slow down before you go to full rebuild mode...
You had a chronic overheating issue recently that you resolved.
Worst case would be you scored the cylinder walls, but it could be much simpler as well.
You noted it is worst when cold and gets better when warmed up and run.
You may have cooked...
Agree with @hottodie
I have carbs wouldn’t want add on EFI
The Thunderbolt is getting impossible to find parts. So that upgrade is worthwhile if any issues in ignition.
If any mods be sure everything is marine ignition protected
That area of the schematic is very cluttered and not consistently marked.
In this case the black dots at "4" is the indicator lamp inside the switch. (not a connection point) A fifth terminal should be present for the ground connection for the lamps.
On a small boat Nav lights are correctly...
I would get the bolt heads off. Grind or drill.
Then spray liberally.
The manifolds should be able to slide off the “studs” until it hits the other engine.
That should give a large enough gap to use a reciprocating saw or hacksaw to cut the bolts bear the manifold
Leaving enough to get a...
Ok so you have a 350 Magnum Multi Point Injection
Computer controlled, cool fuel pump.
Do you have access to any tools?
Voltmeter? Fuel pressure gauge?
Not something you can just throw parts at.
Start simple when it acts up check the tank as i said.
If no gauges see if you have fuel pressure...
Cant find a photo of a 89 but this is a 90 I assume similar V berth with the port holes on the hull side?
Water leaks are tricky to track down. water will flow down but on its way down it may run horizontal many feet before it shows itself.
The port holes are the most common issue as mentioned...