Tach not working properly

[Plumbean]

Originally Posted by Hartley18

No. An alt driven tach is wired to a different set of terminals on the back of the alternator and so will get its signal pulses regardless of the output voltage or the state of charge of the battery bank.

The tach on my 3YM30 was originally wired directly to the stator output on the alternator (an aftermarket Balmar) and would drop out when the batteries were fully charged. It is now wired through a Balmar ARS-5 external regulator and no longer drops out.

[wescarroll]

You have a bad connection or an alternator that is about to go out if it is run off your alternator, if not, I couldn't even guess.

[Cap10paul]

My m 30 Perkins parama alternator light stays on. Removed alt and it puts out 14.5 . Re installed it and there was a small spark. Now tachometer is dead and light still on.
Also oil is coming out of the kill engine shaft and seems like pressure pushing it out. Was coming out of bottom of dipstick tube but I replaced the o ring connecting it to th block and that leak stopped. Any help?

[arf145]

When an electrical thing is working fine until after some physical work is done in the area, a loose wire would be first on my list, as others have said. It's happened to me.

[TJC1010101]

I have a Yanmar 4 JHE..I bought the shop manual over the internet for 15 bucks..because my tach was first sticking.. I'd tap the screen and get it to operate..Now its not working..One of two problems..The electrical connection...at instrument panel..check for corrosion or loose connection it tells me..or might have a bad sending unit that's connected to the ring gear..maybe a bad wire their too..or as they recommend a new sending unit.."That's what the book says"

I haven't got around to it yet..In fact I came hear to see if anyone had that problem..That's Yanmar's diagnosis right from the manual..so I'm sure you can eliminate all these other speculative possibilities..If you get it fixed please post it