electrical problem

[captkirb]

i have a yanmar 37 hp with instrument panel with shut off button. at times my panel seems to disconnect and gauges go dead. i just realized when this happens my alternator doesn't charge batteries. i am assuming there is a loose connection or ground but am wondering where to start. any comments appreciated, thanks

[paul323]

As a start, I would begin to trace wires and develop a rough wiring chart for the boat. A camera, sketchbook and patience helps. I am doing the same thing myself, and in the process have found 3 basic wiring problems - 2 of which were unrelated to the problem I was diagnosing!

Also, if you don't have it already, Yanmar should have a wiring diagram available which will help.

Once you have a rough idea of where the wires go and what they are supposed to do, your ammeter/voltmeter becomes your best friend; just work methodically. But I am betting that during your charting phase you'll find a loose connection.

Not sure of your experience level, but Nigel Calder's book is a good place to start for advice.

[CrazyRu]

Originally Posted by captkirb

i have a yanmar 37 hp with instrument panel with shut off button. at times my panel seems to disconnect and gauges go dead. i just realized when this happens my alternator doesn't charge batteries. i am assuming there is a loose connection or ground but am wondering where to start. any comments appreciated, thanks

I assume that all gauges go dead. Are other electric devices (lights, electronics) still working?
If so it is most likely ground wire for the panel. All wires from the panel go into single harness. it is terminated at a connector(or two). All wires at the engine side go into similar bundle and have corresponding connector(or two). Technically speaking, you can just unplug the panel from the engine by pulling this connector apart. Now, trace a ground wire from engine's side connector. It most likely stands out and goes to some bolt on the engine. Check this bolt. It is most likely corrosion at this point. Or just find all ground connections in your electric system and clean them all.

[mitiempo]

Or a corroded connection on the harness connector itself. As posted there may be more than one. These connectors are often a problem.

[capttb]

I traced a loss of power to the instrument pod this weekend to a 30 amp inline fuse on a 27 hp Yanmar. The fuse was taped into the wiring harness on top of the starter/solenoid, you could make and break the connection by moving the thing around. On schematic it usually shows the power source for pod as connected to

fused ignition circuit

but doesn't show you where it might be. I was tracing the positive power wire with a test light.

[mroman33711]

Why don't you just try testing the altenator with a voltameter, or wire brushing your battery connections. As an electrition i can tell you that wires alway go wrong at connections if the wire insulation is intact. Do yourself a favor and do the little things before the hard ones.

[speciald]

Yes, they hid that fuse quite well. I had one of those holders come apart and suddenly the boat wouldn't start. It took me a while to find the problem. When it happened again that was the first place I looked. I taped it heavily after the second time.