86 tach issue

[Cali Steve]

My tach spins all the way past the numbers and stays pegged pointing about the 6 o’clock position upon startup. Never changes until engine is shut off. Any ideas?

[scaleless]

Does it return all the way to the zero position when you shut it off?

[eaglescout526]

Ha. Oh good ole 84-86 clusters. Chunk just recently started doing this when I replaced the ground cable. Something leads me to believe there is resistance between the tach and ground where there shouldn’t be. 

[Cali Steve]

Yes, it returns to 0 rpm when the engine is shut off.