question about tachometer

[brtnstrns]

So I've had my tachometer hooked up for a while and it used to work fine but now it just sits at about 7000 rpms and doesnt move. Very rarely it will work when I turn the car on and then when i turn it off and turn it back on it will stay at about 1000 rpms then roll backwards to 7000 rpms and just stay there when the car is on and when the car is off. Anyone have any ideas of what the problem is?

 

[Cobain03]

maybe it was installed in a civic and the owner pushed it to 11 thousand rpms and broke it. lol

mine is starting to jump at higher rpms as well ( above 3500)

 

[65ShelbyClone]

What kind of tach is it? Stock, Autometer, VDO, Sun, Stewart Warner, Shelby repro, etc?


It sounds like an internal fault, a short somewhere, or something broken.

 

[brtnstrns]

its an autometer tach

 

[DJCarbine]

I had a similar thing happen to a SUN tach. Take the tach loose if its easy. Open the hood and hook it up directly to the battery, and tap right into the coil. If it still behaves erratically, then its a tach problem. If not, it was teh same problem I had. A combination of a poor ground, and a "dirty" power source. (mine would jump up and down 2,000 RPM in tune to the turn signal blinks )