electrical and ignition 72 tii starting issue traced to tach

[Rustyfe]

traced a starting issue to my tach.  after replacing the pertronix and coil and she still wouldn't start I pulled the tach wire and she fired up as the old girl always has.

The tach had worked okay up to this point, 11/71 date stamp.  stand alone, the tach with separate power and ground and using the same signal wire car ran good until i hooked the signal wire to the coil.  Diode, resistor, capacitor?  Any experience out there?  Will take her home tonight and start checking components.  Any tach schematics available?

any suggestions would be greatly appreciated.

Drive'em,

Rusty

[TobyB]

Sounds like it's grounded.

 

Just to rule it out, try unhooking it at the dash and metering the wire-

that wire runs by its lonesome, so it's possible it's shorted out on

a panel or screw or something along the line...

 

The tachs don't usually fail that way, so I'd try testing the wire first.

 

But then, it might be...

 

Haven't ever seen a circuit diagram for the electronics of the tach-

that's not the Bavarian way, even today.

 

t

 

[Rustyfe]

Thanks Toby, doing more diagnostics, removed tach and isolated the circuit with ground and power.  Everything hooked up as soon as I put 12 v to the tach the engine shut down.  A friend is looking at tach for possible diode or other component failure.  Will keep all posted.

 

rusty