This is a little story about a mystery wire on an '88 boat with a Universal M25XP. This tale is also kind of a further step from last year's fuel line replacement project. A major part of that adventure was relocating the supply and return lines from under the cabin sole to a different route to the electric lift pump and the engine injection pump. This was done when the old Racor had to be replaced and a leaking Facet lift pump was replaced along with it. At that time the mess o' wiring in that corner of the engine compartment was re-organized into a terminal block - no more 3-way crimp junctions just hanging there. 
When finishing that wiring upgrade, there was one odd black wire. It was crimped into the engine circuit black wire that comes over from the panel. The red and black from the panel go the lift pump, in parallel with the hour meter *and* the indicator light for the halon extinguisher over the diesel.
I wondered why they ran an extra "ground" back to the middle part of the boat, incorporated with the fuel lines routing. If the factory guys put it there, I figured they must have their reason, however obscure to me, 19 years later.
The other day I decided to re-route that #12 black wire out of the bilge. Wire was pulled out from it's old path under the galley, thru the bilge and under the nav table, where it went into the mess of hoses and wires below the port side electrical panel area. It is very hard to see or work in that area, FWIW.
I finally used a conductivity probe and decided to once-and-for-all verify the other end of that mystery wire.
Peculiar to the Olson 34, the aluminum diesel tank in under the port side settee, and it has a ground wire screwed to the top -- and that wire disappears aft under the nav. table.... Very Interesting...
Turns out that was the other end of my mystery wire! Why did they pull 12 unneeded feet of wire thru the boat instead to going up 3 feet to the negative bus behind that panel? Hmmm.... only guess that I and a marine electrician at the club can come up with is that the guy doing the fuel tank install needed to run both fuel lines and the grounding line, and he was doing his work before the panel-install guy came in, and just after the engine-install crew did their work.
So, he knew for sure that he could tie into a ground in the engine compartment where he was wiring up the fuel pump. That's my take on it so far -- any Ericson factory guys here to confirm or deny?
Now the wire is much shorter and goes to the neg. bus bar on that port side, behind the main panel.
Another boat electrician at the club told me quirky OEM stuff is *very* common, and he was actually impressed that the builder bothered to ground the tank.
It would be interesting to know if any other 80's Ericsons with their standard Universal diesels have anything like this. Of course, as long as the engine runs, who really cares?
Loren
When finishing that wiring upgrade, there was one odd black wire. It was crimped into the engine circuit black wire that comes over from the panel. The red and black from the panel go the lift pump, in parallel with the hour meter *and* the indicator light for the halon extinguisher over the diesel.
I wondered why they ran an extra "ground" back to the middle part of the boat, incorporated with the fuel lines routing. If the factory guys put it there, I figured they must have their reason, however obscure to me, 19 years later.
The other day I decided to re-route that #12 black wire out of the bilge. Wire was pulled out from it's old path under the galley, thru the bilge and under the nav table, where it went into the mess of hoses and wires below the port side electrical panel area. It is very hard to see or work in that area, FWIW.
I finally used a conductivity probe and decided to once-and-for-all verify the other end of that mystery wire.
Peculiar to the Olson 34, the aluminum diesel tank in under the port side settee, and it has a ground wire screwed to the top -- and that wire disappears aft under the nav. table.... Very Interesting...
Turns out that was the other end of my mystery wire! Why did they pull 12 unneeded feet of wire thru the boat instead to going up 3 feet to the negative bus behind that panel? Hmmm.... only guess that I and a marine electrician at the club can come up with is that the guy doing the fuel tank install needed to run both fuel lines and the grounding line, and he was doing his work before the panel-install guy came in, and just after the engine-install crew did their work.
So, he knew for sure that he could tie into a ground in the engine compartment where he was wiring up the fuel pump. That's my take on it so far -- any Ericson factory guys here to confirm or deny?
Now the wire is much shorter and goes to the neg. bus bar on that port side, behind the main panel.
Another boat electrician at the club told me quirky OEM stuff is *very* common, and he was actually impressed that the builder bothered to ground the tank.
It would be interesting to know if any other 80's Ericsons with their standard Universal diesels have anything like this. Of course, as long as the engine runs, who really cares?
Loren
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