[Fergybikes]

My 67 fastback has a starting problem,hit the key and hear a grunt and nothing.Lites go dim and radio cuts out.Battery is at full charge,also the volt gague on dash shows total discharge.I can start it by jumping the solnoid,but than it dies like it lost all electrical power.So I hooked up a volt meter and its charging at 12.5 to 13 volts.I hav installed some new wiring harness.Two months ago installed new alt.harness and tail lite wiring.But it ran fine the two times I drove it.So any ideas on what's going? Thanks
Fergybikes

 

[mikemstang66]

try cleaning all your battery /starter connections
if that don't fix it them i'd look at ignition switch

 

[Asm109]

Nominal voltage on the battery is 12.8 volts. When running the alternator should be putting over 13 volts on the battery. A reading of less than 13 tells me your alternator is not putting out.

Having said all that, the grunt and lights go dim sounds like a defective battery or a some condition that is causing the starter to draw too much current. There are many possible causes. You could have a head gasket leak and the engine is hydrolocked.
The starter could be bad.