Bad Tach or Regulator?

[Jack K]

I have a 96 170dc w/merc 90. Dunno if I have a bad tach or V regulator. The Tach does move when on the go but only registers to 2000rpm at full throttle.



Is there a way to trouble shoot this problem?



Any info is greatly appreciated.



Thanks in advance!

 

[Russ Charles]

Not sure about the 90, but on the larger motors there 2 regulators, each one having a tach output. Just switch the tach wire to the other one.



Russ

 

[Rob LaMoy]

I agree with Bob. I had the same problem with my outboard and it turned out to be the regulator. Marine tachs do fail more often then auto, but I would bet it is the regulator by what you are telling us. Good luck. Hope your's is cheaper than mine was.

Rob

 

[Jack K]

Thanks for the qwik replies.