Just got boat back from the yard and when I started it up there was no reading on the tach then or during the five hour trip back. Any suggestions where to begin looking? They didn't do any engine work but did repair oil pressure alarm.
If they worked on the oil pressure alarm they must have removed the panel. Probably just a tach wire that detached when they had the panel open.
The oil pressure switch is located near the alternator. If they worked in that area, they may have inadvertantly pulled the tach wire out from the back of the alternator.
So check the back of the panel as well as the back of the alternator for a loose wire.
Roland
[edited for clarity]
If the alt is sending a signal correctly you should see about 9-12 (AC!!) volts between the (usually gray) signal (S Terminal) wire and the ground ( - ) post on the tach. Remove and check AC voltage at the tach w/ a multimeter. Remove and check it there and at the Alt AC out terminal.
Porch : I believe the tach wire is white. So look at the back of the alternator and see if it is attached!!
A thought