I have a 1991 accord lx. The tachometer works sometimes. Where is the sending unit on the engine or transmission?

 

Back then, the tach signal came from the ignitor (aka. ignition control module) inside the distributor. Look for loose/dirty wiring harness plugs at the distributor. I think it's a blue wire - anyone know for sure?

Otherwise it might be connections on the back of the cluster, or even the tach itself getting flaky.

 

Thank you Jim.

Mike