What was Amel’s thinking on the need for an isolated ground for the generator and 185 amp alternator? It seems to confound local Yanmar techs as there are no Yanmar wiring diagrams available to them. Their initial reaction is to want to take the isolated ground out somehow.
This problem started as a non-functioning tachometer. The flywheel sensor ground is indeed bad, pointing as you say up the line on the wiring loom or somewhere else on the engine. A jumper wire placed on the tach sensor ground connector to another engine ground point brought it to life. All was well until the genset was started on passage. Genset started, isolated ground started clicking rapidly, engine failed to start, isolated ground was open, top push button engaged, engine would start, but tach indicated interference.
In my initial thought on the initial tach issue I was thinking a bad ignition switch, but since finding that the tach sensor ground wouldn’t work, it points to somewhere in the loom or on an engine connection in my mind. Opening the wiring loom on the engine would be a big job for me, if it were in the loom from the engine to the helm, that would be another matter entirely. Jumping the ground to get the tach working was too easy. Obviously, there is a larger problem. What do you think the likelihood of the ground short being in the engine wiring loom? Could it be a bad sensor or relay in the same circuit? Does a wiring diagram of this motor with the isolated ground shown exist?