I have a 69 Malibu that drains the battery while running. Battery/ alternator have been replaced. Battery holds a full charge while parked. After about an hour and a half the car dies due to Battery depletion. No fuses are blowing. Only other symptom is key in ignition buzzer sounds after the key is removed but stops when the driver door is shut. Any ideas?

 

what's the battery voltage with the engine running?

 

Re-visit the alternator; check voltage at battery motor running to verify it's charging

 

The alternator was not charging. Apparently somewhere in the car maintenance history, the original style alternator was replaced with a single wire alternator. The regulator on the firewall was bypassed and the cable bundle was taped off and stuck up under the frame. When I replaced the alternator, I put in the old style not knowing the modifications had been made.

 

Good find, now post a pic of your 69 - I have a 68 El Camino in hibernation!