Tachometer replacement/repair

[Jorgeinseal]

Have a 2001 4100 SCA and tachometers fluctuate when tapped, checked connections for corrosion and looks good, think I need to replace or repair, anyone had this issue?

[shrew]

22 yr old tach that is acting funny? I'd just replace the entire cluster. OEM was Faria.

[Jorgeinseal]

Resolved by manipulating the cylinder switch back and forth a few times. No more oscillation when tapped.

[PJHoffnet]

@Joreinseal ... I have the tachs that run off the alternators (one for each engine). They do bounce around a bit it seems, but tend to 'settle out' after the boats been running for a while. I don't understand what you mean when you say you manipulated the cylinder switch to stop the oscillations. Could you please explain.

I'd really like to replace my current tach set up with a magnetic pickup to read directly off the transmission (https://www.sbmar.com/articles/insta...ve-tachometer/) ... but I'll have to save up a bit for that.

[Jorgeinseal]

My tachometer setup is the same. My tachs behaved the same way except when I tapped them, the needle would shift to the right by a few thousand rpm's. Look at back of your tachs and you will see a slotted switch pointing to 6 for the cylinders your engine has, I inserted a slotted screwdriver and moved this switch back and forth a few times which resolved the oscillating problem when tapped. I'd post a pic but can't see a way of doing this.

[Jorgeinseal]

Here's a pic of slotted switch

[PJHoffnet]

Originally Posted by Jorgeinseal

Here's a pic of slotted switch

Thanks Jorge ... I'll take a look at that.