Topic: tachometer works intermitenttly

[Building 3]

Original tachometer, although maybe not for this car, 1966 Dearborn Mustang. Turn car on and it works, then sometimes goes right to 0 rpm and never registers an rpm during that ignition cycle, other times, it will work for a few minutes then go to 0, other times it works fine no matter how long i drive the car, whether it's ten minutes or one hour.  Any suggestions as to what is the problem?  If it goes to 0 it does not come back to working during that ignition cycle. However shutting the car off and turning it back on always gets an rpm, maybe a few seconds, or minutes or it works fine for the whole drive. Any ideas as to what is wrong? Thanks.

[jwc66k]

If the tach is an original (a Rally Pac Tach), it is wired to the coil using the resistance wire. That can be easily checked by looking at the coil "BATT" terminal which should have only one lead to it. If so, the tach's problem is most likely mechanical, the pointer is off it's pivots. The businesses that repaired that type of tach are few and far between.
If there are two leads to the coils' "BATT" terminal, you have most likely have an aftermarket tach and the problem is an internal to the tach electronic problem. It's cheaper to toss and buy a new one.
Jim

[Building 3]

Thanks Jim. It has one wire. A red wire with a green stripe. Any ideas as to who could repair it?

[midlife]

PM me for a tach rebuild recommendation.