Tachometer slow to respond

[Supra87T]

I'm having an issue with the tach working correctly. When I start it the tach sits at 0 but then if I rev the engine it moves up very slowly. I swapped it out for another tach that I have and it goes to about 500 rpm and is also very slow to respond when the engine is revved. In both cases the tach will not rev above 2k even though the engine revs smoothly up higher (don't know how high).

I am assuming this has to be an issue with the ignitor as that is the only source for rpm signal. Does anyone have any other input as to what is going on?

The car is a 87 Turbo 5 speed.

Thanks.

 

[Supra87T]

The water temp and oil pressure gauge are not accurate either. Could this be a grounding issue?

 

[MKIIISupraGuy]

possibly. I vote check your wires including the grounds. You might have a wire rubbing against some metal somewhere, which can eat through the wire insulation and cause all kinds of strange things to happen.

 

[Supra87T]

Figured it out. There was a short in the dash. I swapped all the gauges to a different back panel and it works perfect.