Tachometer RPM gauges

[Lakeshore2016]

Replacing a rpm gauge tomorrow that I hope is faulty. It seems to read decent up to about 4500 rpms. But WOT it pegs out at 6,000. Talking about a 4.3 mercruiser alpha one on a 94 JC 266 tritoon. I can tap the gauge and it does jump around some.

So, does it sound like a new gauge may do the trick... or should I suspect faulty wiring going back to engine as well?

Are there any tell tell signs to look for on wiring going to the engine or on the engine... if my same problem persists when I hook up new gauge?

 

[Scott Danforth]

I would move the selector switch on back of tach back and forth as well as check the wiring connections first before replacing the tach. usually the contacts get iffy from corrosion

make sure the wires are clean. the grey wire is the signal. one end to the S terminal on the switch, the other end to the "-" side of the coil