Tach not working

The tach for my 03 50hp has stopped working. I have a meter and was told to check the hertz reading from the motor. Does anyone know what the reading should be at idle? The tach also has a tag on the back that says it has been calibrated. If I have to replace it will it have to be calibrated again?

Thanks in advance

It could be the tach itself is shot. When you turn on the ignition the tach needle should sweep to zero ?

The needle doesn't move at all. I'm gonna take the dash out Sunday and get a reading on the wire that hooks to the tach and see what kind of reading I get

Check the power feed to the tach. If you have power most likely you need a tach.

Your tach gets its signal from your voltage regulator/rectifier. There is really nothing in the tach to fail. It has a meter movement and a few electronic components to turn the pulses from the motor to a voltage to drive the meter movement.

How is the voltage regulator/rectifier working? Is your starting battery holding a charge? The only way to check the hertz from the motor is with a oscilloscope which I don't expect you have.

I know this isn't much help, but it is a starting point.

My starting battery is holding up good. Not had to charge it and I have a am/fm radio that is hooked to the same battery. Your rite I definitely don't have a tool like that

There are 3 or 4 torpedo connectors in your control harness up by the remote throttle that tie your tach into the motor circuits you can check the connections there and you can check the gray wire that is connect to regulator/rectifier mounted on the motor.

Since the tach "stopped" working I would check to make sure all the connections are shinny and bright and securely joined before I started throwing parts at it.

I believe that the tach is a "12 pole" version if you want to try replacing it. A tach and a regulator are considered an electronic components so they are probably not returnable once you buy them, so if it doesn't fix your problem you are out the money you spent. I bought a new "old stock" universal marine tach that fit my dash hole for about $40, so if it didn't work I wasn't out a small fortune.

Without knowing more about your boat and the serial number on your motor, I am guessing the a replacement tach is about $100 and the regulator is about the same off of ebay.

I'll definitely check out the wires your talking about. I don't understand why it's not working. It was working fine and the next time I fired the engine up it wasn't working. No acting up at all just stopped working.

If you had a digital meter with a DVA adapter (less expensive than an oscilloscope) but still $100 if you have to go out and buy one.

A DVA adapter is a combination resistors, capacitors, and diodes that takes a pulse stream and converts it into a peak voltage. This is somewhat like the insides of your tach and are available on Amazon for about $40 if you have a digital meter.

You could check the DVA voltage at the regulator (gray wire to ground) and the DVA voltage at the tach (+/- input). From that you could determine if it was the regulator, tach, or wiring itself.

Without knowing your skill set, at this point, I would start with replacing the regulator.

Good Luck... Fish On.....

I been doing electrical work for 30+ years in construction and auto stuff but never had any problems with my boat motor. I'll check into getting the dva adapter and go from there.
Thank you this may save me a lot of time and money