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RPM Tachometer sending unit location

GlastronGary

GlastronGary

Member
Good Day Everyone,
I have a 2000 Mercruiser 4.3 190HP in a 2000 Glastron GX185. Recently I have noticed that my tachometer will fluctuate up & down occasionally and sometimes give me the wrong RPM indication. Yesterday for instance I was cruising along at about 30 MPH and my tach was reading 4800 RPM, normally at 30 MPH my tach is at 3000 - 3200 RPM, it eventually settled back down after about 15 minutes to 3100 RPM.
Does anyone know where the tachometer sending unit might be located or am I looking in the wrong direction?
Any help suggestions are appreciated.

Thank you,
Gary
 
No sender involved. Tach signal usually comes from the negative side of the coil via a gray wire. Remove and clean the gray wire connections. There are switches on the back of the tach. I squirt a few drops of WD-40 into them and then exercise them back-n-forth...remember their original settings. Remove and clean the gray wire connections. Also check the main engine barrel plug for corrosion on the pins. If that does not stop the fluctuation it's time to replace the tach.
 
might not be a wiring or a tach problem ...same symptons I had about a month ago, a bad ignition coil will bounced the tach with a loss of top end power.
 
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