J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment RPM sending unit

Patrick,

If it is a 2GM, here are the Yanmar part numbers:
Tachometer part number: 128170-91100
Sender part number: 128170-91160

The tachometer uses a magnetic pickup sensor on the flywheel - mounted on the port aft side near the top of the bell housing. The connector at the sending unit should be checked for loose terminals.
Here are the checks according to the shop manual:

1. Check the connections on the back of the meter.
2. Check the voltage on the wires on the back of the gauge - black is ground, red/black is 12v. If there is not 12 v there, investigate.
3. Check if sender is fitted loosely.
4. Measure the internal resistance of the sender - should be 1.6 +/-0.1 KOhms.
5. Measure the output voltage of the sender - to be 1v or higher.