I was wondering if you all could give some advice as to what might be going on. Basically my car, when starting, will cough twice and turnover. When running it has the exact same symptoms as a bad alternator. 10 minutes after start power will drain out of the battery so its only running off of battery power when started. I have already tested my alternator and battery. The check gages and abs inop light are the only lights on in the car. If anyone has an idea please help. 95 camaro z28. By the way the gages a couple of days were reading just fine. Now my oil pressure and fuel are almost at the bottom.

 

clean the wires and connectors at the battery. look for any heat or corrosion on any of the wires at the alternator and the juntion box on the passinger side fenderwell. check your fuses and relays in the power box under the hood on the driver side fenderwell. relays should all be the same except the abs one so if u suspect one change it with another and see if anything changes.

 

you could have a parasitic drain.the alternator must be working somewhat because the car would die rather quickly if it was running off the battery. your oil psi and fuel psi are at the bottom ? like as in low pressure ? if so try using a mechanical gauge to check the pressure