tachometer advice

[Tom7227]

I have a 19984 SeaNymph with a 90 horse Merc and the tach is bad. It has three wires going to it. I think I need to replace it but want to make sure I get the right thing. Are they all pretty much the same or do I need to shop specifically for this boat/motor?

Thanks

Tom

[boatfixer]

As long as you specify outboard you should be okay. There will be a selector on the back, you will need to set it to 12 pole.

[Tom7227]

Thanks. I've been looking on-line and none of those ask for the type of motor. What am I missing here?

[solbes]

Just something to check before replacing the tach. A couple of years ago I accidentally reversed the polarity when hooking up the starting battery. This caused the voltage rectifier to pop. I noticed it because my tachometer was dead and my battery was no longer charged by the outboard.

I replaced the rectifier myself (easy to do) and the tachometer came back to life.

[marine_man]

That's a good point Solbes...

With repsect to the tach's... some tachs are specific to two stroke vs four stroke and outoard vs inboard.

Make sure you pick the right one for your motor.

I would also get a hold of Valv at KVE Surplus he's probably got one you can get for a reasonable price.

marine_man

[john.wells]

I was going to mention the rectifier, beaten to the punch. You can also blow those rectifiers from a low battery, as they are meant to only maintain voltage to the battery and not provide a deep charge such as an alternator. You can test the rectifier with a voltmeter, but if you don't know how, just pull the thing off and bring it in for testing before you buy ANY parts.

[Tom7227]

That's a good point Solbes...

With repsect to the tach's... some tachs are specific to two stroke vs four stroke and outoard vs inboard.

Make sure you pick the right one for your motor.

I would also get a hold of Valv at KVE Surplus he's probably got one you can get for a reasonable price.

marine_man

Sorry but I can't find that connection. I did a search here and also on Google.

Could you e-mail to weyandt1234@ and then it is yahoo dot you know the rest.

Thanks

[marine_man]

Here's a link to his profile with his info in it:

Valv's Profile

marine_man

[Valv]

Thank you for your suggestion guys, and thank you for your email Tom.

I want to post here so everybody can see. You can change the setting on the selector on back of your motor when it's running.

Put boat in water or with muffs, start motor and turn the small selector even if motor is running, the results can be:

-Way off (eg. idle at 2000rpm)

-Dead ( 0 reading)

-Correct reading

If this does not solve the problem you can try with another tach before replacing rectifier, which will be an expensive part, but it's also the part that charges your batter while going, and you need that for sure.

[boatfixer]

A quick and easy way see if your stator and voltage regulator are working correctly is if you have access to or have a dc volt meter, connect it to the battery. Compare standing voltage with running voltage. There should be a noticeable rise in voltage with increased RPM'S. The tach gets it's signal from the charging system.