Will an "auto" tachometer work in a boat?

[FluffyDog6]

I have an I/O Mercruser 8-cyl 5.0, normally aspirated.

Will something like this car tachometer work, or do I need to buy a "boat" tachometer at someplace like West Marine for much more money?

I assume you tap into the negative side of the coil to attach one of these, no?

[mmwjr]

Yes it will work and you are correct that the sense terminal gets wired to the negative terminal of the coil.

[shrew]

What is wrong with the existing tach?

[HavreDeGrace2400]

Originally Posted by shrew

What is wrong with the existing tach?

yeah.

There's a switch on the back for 4 6 8 options. Wiggling that switch from 6 back to 8 fixed mine last year.

Also, faria will fix them for you for $50 if you mail it to CT.

[FluffyDog6]

Originally Posted by shrew

What is wrong with the existing tach?

It is not working.

Honestly, I haven't traced the wiring yet due to mandatory overtime at work, but I'm spitballing prices for if I need to replace the existing gauge in the dash.

[FluffyDog6]

Originally Posted by HavreDeGrace2400

Also, faria will fix them for you for $50 if you mail it to CT.

What is Faria -- google not helping.

[HavreDeGrace2400]

Faria Beede is a company that seems to supply most of the original instruments. I am assuming yours is too but i don't know. I do know that the instruments in my previous Bayliner were all Faria instruments. And the instruments in my now 2003 2400SE are also all Faria.

Faria will repair those if indeed your boat is also Faria. https://fariabeede.com/2-pages/rma.php

On my previous boat, a 1998 21ft cudy, i mailed them my tach and voltmeter and they fixed them. Per the link above.

But before you mess with that, try what i said. There's a switch for the 4,6,8 cylinders on the back of the tach. My tachometer on my Maxum2400 was reading wrong. Flopping that switch back and forth fixed it.

I should mention that the tach on the 1998 bayliner was seized. The switch wouldnt have helped that one. That's the one I mailed to the link above.

[FluffyDog6]

Originally Posted by HavreDeGrace2400

Faria Beede is a company that seems to supply most of the original instruments.

Thanks -- I'll check it out.