I have an single owner 1979 RX-7 GS with 180KM. after the engine starts the voltmeter is not changing to the tachometer function. I am looking for trouble shooting tips.
thanks.

 

Check the connections to the Choke and Check relay (its on the drivers side inner fender by the clutch master). It controls idiot lights and the volt/tachometer function. Also make sure the trailing coil has the required connection for the tach signal. On a 79 this may be slightly different from my 80 SA but it should be close to the same wiring except the 79 has an external regulator as well (not really an issue here, just pointing out the wiring might very some).

 

also check the foxed.ca site for the manuals and wiring diagrams.

Foxed.ca - Mazda RX-7 Manuals