double RPMs on 1987 Buick t-type

[71mytoy]

The tachometer is reading double RPMs. After changing the ECM and the spark control module. Tried a different ECM also different spark control module. I am asking this for my brother, any help would be appreciated.

 

[BEATAV8]

Caspers Electronics can rebuild those things. Probably what it needs. They get flakey when they're old.

 

[novaderrik]

stock tach?

 

[NorEaster]

Just think of the tach and boost gauge as a curiosity. They are worthless.

 

[71mytoy]

tach is stock

 

[Rafs-T-Type]

Yeah...as said stock tach and boost gauge are pretty much garbage.