Mercury Tachometer

I recently bought a Teleflex

I recently bought a Teleflex Marine Tach from Cabellas the catalog claimed the it would work with all electric start motors. The problem is that the instructions don't include my motor a 79 Mercury 80 hp with thunderbolt ignition can anyone tell me how to install this tach with my motor? The tach also has setting that are based on how many magnetic poles the alternator has does anyone know how many this motor has?

Thanks in advance

David

" David,

There are

" David,

There are three important posts on the tach (the 4th takes 12 volts DC + for the backlight).

1. 12 volts DC + supplied when key is on
2. 2-7 volts AC signal (when engine is running)
3. ground

There should be directions included with the tach, which tell you how the colors and settings go, but if not my 86 inline 6 uses the 6P setting and yours probably does too; I believe this is exactly half of the number of poles (12).

You should have a wiring harness for it, but if not there should at least be a harness (with a half circle shaped plug) coming out of the control box. There are three leads; I believe the ground is black, but it's easy enough to test for. The 12 volt + will be "on" when you turn the key on, and the signal is what's left.

Jon "