Jump to content
Sign in to follow this  

Tacho (Not Idle) Fluctuating

Recommended Posts

Gday all,


Hope you guys could give me an idea into what could be happening.


Bit if background, I have a '73 240z running an L28 with a 280zx electronic distributor, MSD 6A ignition, stock tacho with MSD tacho adaptor/booster.


My issue is the tacho fluctuates with every indicator flash, drops dramatically when the headlights are on (relays installed) or if my heater blower is on.


Note, driving/revving does not change, purely a tacho reading issue.


I have just bought a new battery and had a 280zx internally regulated alternator installed about two years ago.


Any ideas what is causing this fluctuation? It's bloody annoying!





Share this post

Link to post
Share on other sites

Hi Adam,


One thought is the tacho is quite sensitive to fluctuating supply voltage, given you have covered a lot of bases with the (+) positive side of the supply, I would be checking the quality of your (-) ground connections. Try taking the negative supply to the tacho direct with a new wire to a nice clean ground point. Poor ground connections unfortunately dont raise there ugly head until there is load on the circuit making tracing a real pain in the neck. Hope this helps, and good luck.



Share this post

Link to post
Share on other sites

That was my next step Billy, cheers.


I am all ears for any other suggestions.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this