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2660 Views 6 Replies 4 Participants Last post by  NcChopper
Question: My tach is acting up. It goes up to 2000 rpms and then goes backwards. I've changed nothing. I made sure the connection at distributor is good. Sound like a ground prob or do I have a wire messed up at the distributor?

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Tach Problem


The coil can cause erratic tach operation. I had this problem and DUI told me to change the coil. I did and the problem was resolved.

And, yes it could be a bad connection on any of the three tach wires, power, ground or tach signal.
Thanks, Neil I did have the distributor cap off to inspect everything and maybe I bumped something loose. I'll look there and make sure everything is tight. The coil is just a couple of months old and is an MSD. Sure hope it's not bad already.

If I remember correctly I was having a problem with my fuse to my tach and was sometimes getting the same response. When it starts acting up check the fuse and the ground.
Thanks Neil and Glenn. I checked all the wiring and everything looked good and the ground was secure. I, luckily for me, had the original coil that came from the factory and replaced the MSD coil I had installed and it works good again.

One more suggestion Chris,

And it is a long shot--but the same thing caused my Tach to jump around like a Mexican bean.

I found that insulation on the wire to the right rear turn signal (of course it could have been any wire) had wore through at the bend where it enters the turn signal housing and the bare wire was "very lightly" continuously touching bare metal--it was causing the problem.

Worth a look see...

Jon Ukman
Thanks, Jon. I'll double check that just to make sure. Coincidentally, when I changed the coil out it does fine now but ya never know.

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