I have a Teleflex 0-6000RPM gauge that is inop...I am going to assume that it is the original (the boat is 10 years old). I'd like to replace the gauge but a buddy said that it could just be loose wiring or a bad connection. Without getting too expensive, how would I go about ops checking wiring/ gauge to narrow down what is the issue? BPS San Antonio has the 0-7000 gauge...if I need to replace this gauge, will the 0-7000 work as long as it fits? Thanks in advance...

Hey Mytus, first thing to check is the rectifier. That is what puts out the signal to the tach. Easiest way to check is with engine running check the voltage at the battery. At idle you should get a reading of at least 13.5 volts if the rectifier is putting out a charge. Most times when a tach is not working it is due to a faulty rectifier.

if you have a water cooled reg here is how to check it

http://forums.iboats.com/showthread.php?t=190636

sometimes moving the settings knob on the tack back and forth a few time and returning it to its original position cleans the contacts inside try that

If all that fails check all wiring harness plug connections. Had one the other day that it was corroded causing tach not to work.

Thanks to everyone...I'm going out Thursday with an electrician friend. Hopefully this is an easy fix. I've already found the replacement rectifier online, if necessary, and have a new tach lined up if it's not the rectifier.

Just a tip. Check the tach ignition post for voltage while running with a test light. If you get any voltage their something is wrong with the tach (pole setting, 12v supply or groung). If not check same wire at rectifier-regulator. If you have any voltage their it is a connection in the wiring harness. If no voltage their it is the rectifier-regulator. PS: the tach does have to have 12v and ground to work.

...ok, here's what happened. Cranked the motor...at the battery at idle, 12.40 volts. Rectifier...?

maybe the stator

What is voltage before cranking? Does voltage increase with rpm? What did you find on system test? Do`nt really understand why you are checking voltage at battery. 12.4 v is good for idle. The current that the tach picks up to work does start at the stator. Are you having problems with battery going down while on the water also? What motor do you have? I have never seen an outboard charge much over 12v at idle, with all being right.

The motor is a 98 Johnson 90hp. The motor runs great...no problems with any other electronic system that I can tell...all other gauges function as designed. When we revved the motor, the volt charge didn't change. When I go to charge the battery...it's usually run down to about 75% capacity.

Most likly is the regulator from what you have said. Would recommend servicing the cooling system, if you hav`nt lately. When the waterpump starts getting week on these motors, it can overheat the regulator and knock it out.

Thanks for the info...hope the replacement of the rectifier fixes my problem.

...uugh, now what? I finally got the replacement rectifier...and noticed on the old model that one of the yellow wires is striped, grey and yellow (didn't notice that before; it's very light grey). The new one is not...just one red and two yellow wires. I would assume that there's a reason that one of the yellow wires on the old part identifies something important...anyone have an idea as to what I need to do from here? By the way, the engine is a '98 Johnson 90 hp SPL. [If I can get the camera from the wife, I'll update with a picture. I have not removed the old part...yet]

Call the service mgr at the dealer. My engine is older, and they sold me an exact replacement.