First a little history. It's a 1989 Formula LO3 I have had since the mid 90's. Always a great car. Never any issues till several years ago it wouldn't pass smog. Still ran great no issues at all. Would literally spring to life in seconds, idled smooth and ran very well. But still wouldn't pass. Several shops couldn't figure it out either so it was parked for a couple of years. Started it regularly and couple years later I found the problem. Warn shaft bushings in the TBI sucking air (still running great). Last spring I bought one of those extremeFI units off of ebay with a few mods/upgrades and installed. Got her running again but my old Snap-on scanner died so had no way of tuning. Then life happened and wasn't able to get back to it till now. I got WinALDL and the cable but now heres the problem. With key on everything lights up (fuel pump seems louder than it should be). When I turn key to start car looses all power (no lights, buzzer, anything). I have to let it sit for a few minutes and power comes back but when I try to start everything goes dead for a few minutes again. Any ideas would be greatly appreciated.

 

loose / bad battery connections, bad ground from battery to body, or fuseable links (near starter) might be bad,...

 

Agreed. Also check connections at starter. If all that good I would suspect the ignition switch.

 

Doubtful
The fact he looses power when in the start position indicates the switch is operating some item ( the starter ) that is sucking all the juice out of the battery.
If the switch was faulty ; nothing would change when it was operated

 

How old is the battery?
What Volts are showing on the battery before and during the key being turned?
If the battery is not fully charged or on it's last legs it will give the symptoms you indicate.

 

But possible since not all the connections are being made (bad connections, broken internally etc). I only saw that cause it happened to me once.

 

Thanks everybody. I have tried 3 different known good batteries. Wasn't sure of the condition of the original since the car has been sitting (battery disconnected) for a few years but was nearly new when I parked it. I didn't check the actual output of them since they will start my other cars. Checked all connections at batt, alt, & starter and all are tight. Didn't know if there was a circuit breaker or something somewhere that was resetting. I was thinking that was why it comes back after a few minutes.

 

I had the exact same thing happen to me before in my truck about a month ago. It was a loose connection at the starter. It would allow enough juice through to power everything until I tried to start it and the amp load spiked.