Rpm on tach goes down when rev engine? Why?

[hunter_alexander]

Rpm on tach goes down when rev engine? Why?

 

[pontiacgp]

what brand of tach do you have did you recently install the it?. Have you checked the wiring?

 

[hunter_alexander]

Sorry, should have stated. It's the factory 1987 442 tach. The clip has already been soldered on the back.

 

[Wageslave]

I would suspect electrical noise on your tach wire. Is the tach wire from the distributor close to any of the plug wires?

 

[pontiacgp]

what have you done with the car just before the problem started?

 

[hunter_alexander]

I don't think so. Have to look.

 

[hunter_alexander]

Didn't do anything to the car yet. All original. It was working fine. Then it just started dropping to zero when I revved the engine.

 

[Wageslave]

Didn't do anything to the car yet. All original. It was working fine. Then it just started dropping to zero when I revved the engine.

It could be as simple as the plug into the distributor is loose. Try unplugging and cleaning the connection into the distributor and see if that helps.

 

[hunter_alexander]

Ok, not the dist wire. The tach sits at 1k until u rev the engine then drops to zero.

 

[hunter_alexander]

Just an update... So unhooked the tach wire on dist and ran it. For a bit the tach was still doing it so def something with the gauge cluster. Guess a rebuild is in order.

I seem to remember somewhere on the web someone hard wired the gauges to bypass the flimsy plastic circuit board on a cutlass before. Anyone know what I'm talking about?