Tach wires on Mercruiser 3.0

[Coxn]

The tach gauge on my 2002 Mercruiser 3.0 is acting up. Won't read steady. I've checked all the connections on the back of the gauge. All look good and the selector is set appropriately for a 4 cyl engine. Where does the pulse wire for the tach connect on the engine. Thought I could check for steady pulse with a meter...

 

[AllDodge]

It is a gray wire and connects to the negative side of the coil

 

[kghost]

Here is a schematic, IF your ignition is this type. But it will show the basic wiring and colors.

One thing about tachometers that are getting old, Some times they read incorrectly. If you turn the selector from the 4 cyl position to the other positions a couple times then back to the 4 cyl position, It may solve your issue. Do this with power OFF.

 

[mjricha83]

Here is a schematic, IF your ignition is this type. But it will show the basic wiring and colors.

One thing about tachometers that are getting old, Some times they read incorrectly. If you turn the selector from the 4 cyl position to the other positions a couple times then back to the 4 cyl position, It may solve your issue. Do this with power OFF.

View attachment 36780

hello, I'm sorry this is an older post but do you possibly have a schematic like this for the 2.5 4 cyl with points? i was looking for exactly this type of diagram. thank you!

 

[AllDodge]

 

[mjricha83]

awesome

View attachment 36959

awesome thank you!