MrMaterial

Hello guys, sounds like I'll be joining the bandwagon of randomly shutting off F-bodies.

My '91 GTA 5.7L TPI is randomly losing it's connection to the battery (it seems.) The first time I noticed was the day after I drove it on this 8 hour trip to get back to school during spring break. On the drive I encountered tons of rain, snow, and other things I wasn't expecting and my tachometer decided it was about time to start floating anytime I bring it to over about 1500rpm (unrelated?). Otherwise the car drove fine and never did anything weird the whole drive.

The next day I go to start it and in the middle of cranking it suddenly stops. I hear clicking from a relay at the passenger kick panel, though I don't remember if it was clicking as I turned the key or not. I got the impression that I had a dead battery and looked at the headlight switch just to make sure I didn't leave it on or something (turns out I didnt). After taking the key out and in again I gain hope as I see the dash lights return and I get the car to start and everything seems just fine.

This cranking issue happened one more time, I got the car running after trying a couple more times, then drove a few miles for some errands. On the last leg of my trip, the car dies in the drive thru. I manage to get it to start within about 10 seconds and the car idles fine the rest of the time I am there (about a minute, I also turned the cooling fan on just in case although the engine temperature wasn't too high.) On the short drive back, the car shuts down, but picks back up again so that I don't have to crank it again, 3 times in about half a mile!

All these times I don't entirely realize what happens when the car shuts down, I generally associate it with the ignition problems I've had before, but today in taking a short drive to starbucks (not even fully warmed up) the car shuts itself down right as I was parking. I don't touch anything (key is still on). As I rest to a stop, I realize that my radio has turned off and there are no lights in the dashboard. When I put it in park and go to turn the car back on again, it's completely dead. I keep trying and about 10 seconds or so later I get life again and the car starts up as if nothing is wrong. I pull forward a little more into the parking spot and just let it sit there idling, interested in if the car will shut off again. Within about a minute everything powers off as it did before, like the battery is disconnected.

I drove back home about 40 minutes later without any more issues, but I've started looking at the factory service manual to troubleshoot cranking problems. My real problem is that the car doesn't shut off reliably enough for me to do the troubleshoots that the service manual suggests. Upon reading some of these threads here with related problems it seems like vats could be an issue, I have an aftermarket "viper" security system that the previous owner had installed, perhaps a fusible link or cable from the battery, or perhaps something else altogether.

Note: For what it's worth, my new coil is already rusty. I think water might be getting on that system. I fixed the sealing situation with the hood so hopefully that doesnt get any worse. Also any time it rains, my battery is covered in water. I dont really know the extent of how wet the battery and cables get, but the factory guards and looms are still in place for what it's worth.

bop11

When did you replace the battery? You could have a bad battery terminal internal to the battery. The fact that you lost all the dash lights seems to point to a power disconnect at the battery. Either positive or negative side could be the culprit. Also check the grounding from the battery to the block. Also the battery side terminals may be lose Follow the positive smaller cable and you may come to an isolated junction box with several cable s bolted on a stud. Make sure these are clean and tight. This feeds the ECM and fuel pump relay and others.
Running an alternator with the battery disconnected can fry the diodes in the alternator so get it fixed.

blacksunshine'91

iTrader: (10)

While you are checking the battery terminals, make sure you check for corrosion as well. I had a issue that was kind of like yours and it ended up being some corrosion inside the battery terminal.

MrMaterial

The battery is not even a year old, but upon looking I found that the battery wasn't mounted correctly, and the negative cable was a little loose. So far I have tightened both cables a little bit since they seemed to be less than snug.

Thank you guys for your help, come to think of it, I had a problem just like this with my old VW, but on this car I just assumed it was something more sophisticated than a battery cable.