Yanmar intermitant tach and instruments

[Celestialsailor]

Just thought I would get a little input here before I go back to California to work on my little ship. I have a Yanmar 4JH2, 44hp. diesel in my Ingrid 38. When I first installed it, everthing worked just peachy-keen. Later the tach began to fluctuate intermittently along with the gages (temp&oil). Now the tach is dead completely and the gages work intermittently. My batteries are very flat. I'm doing a total refit, so the batteries will be the last thing to go in. To start the engine every once in a while, I turn on the battery charger and charge what life I can into the dead batteries. They do not hold a charge for long but it is enough to fire up the Yanny. I know the tach works off a trigger off of the flywhell but my question is. Does the bad batteries have something to do with all this? Like not enough juice to build a field in the alternator or something?
Any input would be appreciated.

[Alan Wheeler]

That is possible. What happens if you leave the Charger on while the engine is running??
Also check the obviouse. On the back of the panel, there maybe is a plug to the wiring loom. Check it is plugged in tight. I had that on a 42ft twin engined launch last weekend. No instruments on one engine. Plug was loose.

[Celestialsailor]

Thanx Wheel...I did check the plug and just thought about leaving the charger on...however, I am 2400 miles from her at the moment. I will rry that upon my return.

[Alan Wheeler]

So you aren't going to just pop down to the boat and get back to me in the next half hr or so huh??

[Celestialsailor]

I wish!!! I actually have to do some work at home here. Looking forward to getting back and tearing up dollar bills again!

[Ex-Calif]

I would work the known problems first - bad batteries - and proceed form there.

When we bought our boat the "idiot" light package was not working. I bought a set of those pin cleaning brushes and spent a day cleaning all the connections to include opening up the gauge panel and cleaning the light bulb sockets etc. It all came back to life except the glow plug light and the alarm horn. The horn needs replacing - juice at the pins - but I'll be darned to figure out the glow lights. At least the oil pressure, water temp and charge lights are working.

[Chief Engineer]

Check your ground (earth). From Panel to engine