Tach Problems

Hello new here but I have a 74 mgb and when i start or just turn on the ignition key the Tach. goes all the way up and stays?? But the tach dosent work?

Any Help?

Hi Jason, welcome to the MGE !
Check/clean ground on the tach.
Also check connection of white/black wire connection at coil and tach.
In addition check connections of green wire to voltage stabilizer and ground of stabilizer.
Is your fuel guage sender working correctly? (if not this could indicate a voltage stabilizer problem)
Hope this helps.
RS

Given the symptoms you describe I fear there is a problem inside the tach. Obviously you should check the connections - but this sounds like a blown transistor or other component failure.

You should update your profile to show your car's year - there were a variety of tach circuits used.

I have fairly accurate schematic for at least one (and possibly two) tachs. The units use an obsolete germanium transistor - it can be gotten with difficulty via the Internet. If you are not handy with electronics, you can send it to Nissongers for rebuilding. I understand that they gut the electronics and substitute a modern circuit. This may require minor rewiring depending on the year of your car.