No Tach - Merc L6

[dirtyoldman]

I have a 69 Mark twain boat with the merc 160 HP straight six. My tach isn't operating. The guage goes to 1000 RPM;s when the key is off and back to aero when turned on. I know I have the wrong distributor on here, but where does the tach get the signal? Do the guages fail very often?

 

[Coors]

Re: No Tach - Merc L6

Tach signal from the - terminal on the coil.

 

[Rhadley]

Re: No Tach - Merc L6

I'd disconnect the wire at the ignition coil and measure resistance between the wire there are on the back of the tach. It might be broken or corroded.

 

[lorax]

Re: No Tach - Merc L6

It's the rectifier.