Problem with Tach?

[smallieobsession]

So a couple of different times it seems like my tach is soff by almost 1000 RPM's. I think it mostly happens when I first launch for the day and make my initial run somewhere. I look down and the tach might say 6000 but I'm only going about the speed I would typically be going @ about 5000 RPM's....plus, I can tell just by sound of the motor that it isn't really wound up to 6000.

So then when I get to where I'm going and shut the motor down, the tach still shows about 1000 RPM's. When I fire it back up and run somewhere else the tach seems to be back to normal except that every time I stop, it still shows about 1000 RPM's.

Is a Tach something that needs to calibrated or something???? How do I get it back to normal????

Appreciate any guidance.

Smallie

[marine_man]

Take a look at the back of your tach.. is there a calibration screw / or screw marked cal?

Otherwise I think you're out of luck.. it's probably time for a new tach.

marine_man

[311Hemi]

Never mind, I see you say the tach is off when you shut down the motor.

[smallieobsession]

been away for couple days...I'll look for that screw....if not there...new tach makes sense. Marine man....thanks for the reply!

[wastewaterguru]

Don't go replacing the tach without doing a electronic check of the output wires coming into the tach. Best option is borrow one from another boat, make sure it's set to the correct number of poles for the stator on your motor (most tachs have a knob on the back). Connect the borrowed one and see if it has the same issue or do the electronic check in the book.

Tach signal can be off for several reasons including a bad voltage regulator, poor ground, bad stator, etc.

Check it first before buying a new one.

[marine_man]

There are different settings / poles / etc, but regardless of all of that, the tach shouldn't start out at 1000 or end there when you shut the motor off.

marine_man