paulram

Tach Working Then Died Suddenly

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My tach didn't work when I bought my car.  I found that is was disconnected.  I ran a new wire from the coil to the back of the tach last night.  It was working when I took it out today for my first drive of the year.  After driving about 5 miles it stopped working.  Connection is good/new.  The only thing I can say is that although it was working, the RPMs it read were very high (2000 RPM at idle, 5500 RPM in 4th at 55mph).

 

If the only connection is that one, is the tach no good?  Seems odd it was working and just died suddenly.

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Points to consider...

 

conventional ignition? (no pertronix or aftermarket CD system)--they can affect tach operation, from a high reading to not working at all.  

 

Didja connect your new wire to the same terminal that the old one came from?  And why did you replace the wire in the first place?

 

Engine running OK?

 

Tachs don't fail very often (but they can)

 

An erratic tach can often be traced to a worn distributor point plate (the part that the points are fastened to, that moves back and forth with the vacuum and mechanical advance), so that may have been the cause of the high reading.  

 

Let us know whatcha find.

 

mike

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Possible grounding issue? Sometimes its as simple as running a new ground behind the cluster.  My tach wasn't working, nor was my fuel gauge and the new ground wire fixed it.  Not sure if that's the case here, but its simple enough to give it a shot. 

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(edited)

Car has Pertronix.  The new wire was run as one of the previous owners did an engine swap.  Unfortunately cut a ton of wires and left alot to be desired.  All other gauges are working.

 

When I started it this morning, it was working for a bit and then stopped again.  I just took it out at lunch and not working. I do not know if I connected it to the same terminal.  There was a wire to nowhere off one terminal and I used that one.

 

Its a wiring nightmare as far as peripherals.  No dash lighting, used the hazard switch assembly as hot lead for the radio, wires to nowhere everywhere.  I've isolated that alot of them are from the smog and can be removed.


I was under the impression the tach was a direct connect and no fuse involved???

Edited by paulram

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i have a pertonix, I had the same issue a couple of months ago; I pulled the fuse, bent the metal contact fittings inward and behold, tach has been wokring fine ever since. it's worth a shot, just saying

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