So I replaced my starter motor in my 1992 Cadillac Eldorado 4.9 V8 PFI since it wasn't engaging the flywheel gear, just whizzing out, although I could get it to start after several tries. Unfortunately this didn't fix the problem, the starter would, just like before, clink then whine out, but I could still get it to engage and start after several tries by moving shift lever all the way back and forth and wiggling.
THEN! last Tuesday took the wife to a grad night meeting and parked in the school parking lot for about 20-30 minutes. Turned the key to run, all instruments lit up. Then turned to start, all instrument lights go out and no crank, no sound. Dome lights stay on, headlights work fine (dim a little), but nothing I can do to get any satisfaction. Had to get it towed, but not to shop (no money for shop work ).
Took battery in to Napa for a test, and, good news? ...guy at the shop said it was bad. Got a new battery for $50 since previous was less than 3 years old. Sweet!
Hooked up new battery, excited that this was going to fix it. NERRRP! Same blacked out instrument lights. BTW When key is in run position, computer is saying no gas, battery at 0.0 volts, coolant at -40°F (not true, live in California), whatevs.
Tested starter relay in rocker panel, it works fine. Checked my wiring onto rebuilt starter motor, looks ok. Checked wires near exhaust pipe, not burned or melted.
Wondering what could have happened in 20 minutes in parking lot that turns my car into a useless garage sculpture? Any help in diagnosing this would be greatly appreciated.

 

Back in the early 90's GM had some issues with positive battery posts leaking acid. The acid would corrode battery cables under the insulation. You need DVOM to do some testing. There are two positive battery cables one goes to starter the other to relay center under plastic cover on drivers side fender well. Check to see if you have battery voltage at ends of both cables. If insulation is split or copper wire is a burnt red or black you will need cable(s) The cable end kits sold at parts store should be considered a temporary fix since it's the wire that's failing

If you search this condition "4.9 no start" you should find many threads related to your concern. 92-93 eldo,seville ,and 94-95 deville were all pretty much the same with causes

 

Thanks Slow Roll, I checked the positive cable for continuity with my multimeter at the starter, alternator and fuse box, got 0.00 resistance. (Cable looks OK.)
Then I checked the fuses (should have earlier) and the IGN 50 amp Maxi fuse was blown. Got down to O'Reilly and dropped $8 for 2 new ones, popped one in, and it starts! Yay!
Turned her off, put shields and covers back on for triumphant test drive. Errrh! Start motor still needs 3 tries to engage flywheel gear! Whines out like the original starter motor. Took it on a drive anyway, not so triumphant.
Trying to figure out why rebuilt replacement starter from BBB Industries is acting just like the original. Was hoping the problem was caused by the old battery being bad.
Going to try shimming the new starter. Will update.
Thanks again for the suggestions.

 

UPDATE: the rebuilt starter was defective! The pinion gear was not extending when starting (took it to a local shop in Sacramento where they bench tested it). Bought another used one from the shop for $50, dropped it in, my car starts every time now. Lesson: always include the replacement part as a possible source of trouble.

 

Good Job!