Original tachometer troubles

[fvike]

This winter I swapped to an original tach cluster, and all is working well, except the tach itself. The car will not start when it is connected, but the tach is working. When I disconnect the tach ground wire, the car starts, but the tach doesn't work. When I tried to startin it by holding an grounded circuit tester between the coil nad the tach ground wire, the car started and the tachometer worked.

Is there anything inside my tach that might be broke ?

I've got an Pertronix Ignitor in the original distubrator and an accel supercoil.

 

[fvike]

c'mon people! TTT

 

[limey66]

Dunno man, just bumpin' you back up the list.

 

[BarnStang]

Not sure how the stock style tach is wired, but say a simple store bought tach would trigger off the coil. If the car dies when you attach the ground wire for the tach, then the tach must be shorted internally? It sounds to me like you are grounding the ignition and the tach is the only thing between. Assuming it's wired corrrectly of course. Do this if you can. Borrow or buy a cheap tach and try it out using the same wiring. Just extend the existing leads temporarily to see if a different tach works ok. If it does, then I would guess the new tach is defective or failed in some way. If it still dies, then that would be a good problem. I would have to look over the hook up again.