Tachometer still not working

[ttikalsky]

I finished troubleshooting the tachometer, I hope. Maybe someone here
can confirm my findings.

Turning on the ignition, motor not running, causes the tach needle to
spin 1 complete revolution ending up pointing straight down. When the
motor is started the tach needle will occasionally appear to work but
not with any consistency. Ussually points straight south. I replaced
the drive unit on the motor with no change. Tonight I began removing
wires 1 at a time and testing for any change. Eventually I ended up
removing the guage and connecting a jumper wire to the power and 1 to
the ground. At this point the needle aligns to zero. When I add a
single wire to the "S" terminal the needle spins all the way around
and points south. This happens even when the wire attached to the "S"
terminal is new wire still on the spool. I'm thinking the guage is
junk. Can anyone confirm this?


Troy, Waconia MN
1983 FC33