Uh oh...voltage crash and now won't turn over

67dartgtgo said
Hi Guys,
The other day I was out as a cruise night and noticed my voltage all of a sudden became erratic on the low side at idle. I was actually idling through the parking lot when the voltage dipped and caused a stumble and stall. At increased rpm the voltage recovered and all was good. Checked connections...all good. Got her home and put her to bed. Last night when heading out for test drive she ran ok but the voltage was a bit low @ 11 volts...always runs a solid 13. Again checked all connections, Alternator connections as well, changed vr because I just happened to have a new in the box one in the cabinet. All grounds are good. Battery voltage is 12.4. Now the starter won't even crank....like it's not getting any power at all. Ignition key to on and voltage gage @ 12 volts, key to start and voltage crash to 10 volts or maybe lower as that's the bottom range of the gage. Everything works with the key in the on position...lights etc. Fusible link appears good. HEI conversion for over 2 years. Car was running awesome prior to the other day.
Thoughts?....you guys are the best by the way.

Might want to jumper it at the starter relay and see what it does. (some sparks at the relay terminals is normal)
Also check that engine harness connector at the rear passenger side of your engine if you have that connector.
Those connections in that connector can get sketchy and cause charging issue's.

The fact that the voltage drops when you try to start it but it doesn't crank points to low battery amps, or a possible ignition switch/relay/starter problem.

Of course this is just basic first steps to diagnose.

You want to connect "Battery" to "Solenoid" to test for cranking.
This will bypass the entire key switch and ignition system and should crank the engine.
Let us know what you find when doing this.