Just got a new motor etc and the rpm jumps a little on start up and then dies out. Not sure if the speedo works either. What do you guys think? Time for a rebuild on the tach. I read up and it seems they go pretty easy.

 

Mine is doing the same thing...but my speedo works fine...craziness I tell ya...craziness...

 

check your wiring to see if something got cut, trans too

 

Did you reattach the collective grounds on the front of your bumper??? I forgot them one time it drove me crazy for like a week and then i was like oh....god im a dumb ***, ran fine.

 

can i get a better location of this ground.. I just did an engine swap and everything is working except the tach

 

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/engine-swap-now-i-got-some-issues-tach-boost-801709/

 

Yea there is a write up on putting new capacitors in the circuit board. This is most likely your problem.

http://www.umsl.edu/~tch9gd/Tach.pdf

 

I bought extra capacitors when I did mine, PM me if you need them.