troubleshoot Tachometer

[steve mcintire]

My old Starcraft has a1996 Mariner 60hp ELTPO. The Tach has been working fine until last weekend. I was running wide open. Around 5000 RPM (based on past performance). the tach showed 2000 rpm and when I shut off the outboard the dial did not return to 0 A visual inspection under the dash showed nothing abnormal. The tach was install by the local Merc dealer at the same time they installed the new Mariner. The unit has approx. 400 hours of use.
I value all input. Thanks in advance

 

[Chris1956]

Most tachometers will "zero", when power is applied, engine off. If yours used to do this, and doesn't now, check the + (purple wire) and - (black wire) for proper voltage. If the voltage is good, it is likely the tach is bad.

You should use an ohmmeter to test the signal wire to the engine. Resistance on that wire should be zero.