Long time reader, first time poster. I have a 91 Z28, 75,000 miles, 5.7L TPI (stock other than Hypertech chip and thermostat).
While driving in hotter temperatures yesterday (91 Fahrenheit) my car started to lug or feel like it was down on power. I could "lightly" throttle the car and maintain or gain speed (70 MPH) but any serious throttle would cause the car to surge. I noticed that I had lost accessories (radio, gauges, signal lights) somewhere along the journey home. I limped the car back and when I tried to pull it in the garage, it sputtered and stopped running. I have a bit of an incline on the driveway.
I let it sit and "cool down" for about an hour. When I went back out to boost it to get it started and in the garage, I decided to see if it would start. It fired right up and all the accessories were working as if nothing was wrong. I have the FIL coming by to check on fans (working or not), but the car normally runs around 155 on the highway and in regular stop and go driving. I should also note that I had the AC on (or the "cold air" blowing) so I am going to check if that system is working, or if it just needs a recharge.


My initial thought was the alternator but when it started back up right away and everything was working fine again, I assume it was overheated, but is that normal?

 

WhtLitnin
That sounds like a Alternator going out and not overheated

 

If it was the alternator though, should I have been able to start the car without a boost? I would have thought the battery would have been dead. I had good interior lights, under hood light and when it started back up, full headlights.

 

Well, you said you lost I lost accessories (radio, gauges, signal lights) somewhere along the journey home.
It depends on how strong your battery was/is. You have a voltage regulator incorporated in the alternator that supposed to regulate correct voltage. If it goes on the fritz, you can lose gauges and such. And when it cools off, it would work. Hard to say.
I would have it checked under a load at an auto parts store and see if if its working. Take the battery too.

 

Thanks Bob. I will have them both tested at Parts Source tonight.

 

I'd lean towards alternator, mine was failing and would cause the battery to drain while driving, had fans cut out due to power loss and car overheated :/ new alternator installed, car runs 150 degrees at hottest and takes off with a vengeance. My car would sometimes charge the battery enough to restart the car, but eventually it'd fail while driving and leave me stranded if I had to shut the car off :/

 

 

Thanks for the advice. Gonna pull out the alternator and the battery and have them both tested.

 

Best of luck let us know how it goes

 

Turns out it was the alternator. Bearing had almost completely seized in it.
Thanks for the help.