Tach stops

[brackie1]

I've had my 1977 for 6 yrs. The tach has worked fine except for 2 yrs ago when it would only get to 4200 no matter how fast I went. As it turned out the alternator was bad. Replaced it and all was fine until today. Same thing happened again. Tested the alternator and it was fine. Tested the battery and was fully charged. Could it be the coil?

[18Fiatsandcounting]

I'm assuming you have the original ignition system with dual points/condensors, so check that out thoroughly. Replace points and condensors if they're old, and make sure the point gaps are correct. Since the tach essentially "counts" pulses from the ignition system and converts that to a tach dial reading, if the ignition system is marginal it may confuse the tach.

It could also simply be a bad tach, but I'm leaning towards the ignition system at this point.

-Bryan

[brackie1]

No have a electronic.

[18Fiatsandcounting]

Hmmm, you've got me stumped then. If you put in an electronic ignition and the tach stopped working right, then things would make sense. But, in your case it worked fine for 4 years and seemed in the past to have something to do with the alternator.

Maybe someone else on this forum has seen this before?

-Bryan