Re: Custom Center Console Rebuild
You said that you had tried a different tach so I guess that rules out that possibility.
I would check all connections first. Not sure on the wiring for your particular motor but there should be a wire from ignition supplying 12V+ to the tach, a ground wire and a sender wire. I'd check for the 12 volts with a volt meter. If 12 v is present, then I would check for continuity in the sending wire. Assuming the wire is good and you are getting power form the signal wire, I would double check the range you have the tach set to and make sure that it is set properly.
The signal lead is fed by the recitifier I believe, so that would probably be my next stop. I would imagine there are steps to troubleshoot the rectifier assembly somewhere here on Iboats. I am no expert, just try to provide a neutral opinion on the troubleshooting process. If you have already done all of this, your best bet is to start at thread in the section that covers your motor. I guarantee that you will get more and better help than you get from me. Good Luck, I'll keep an eye out for your solution.