So, I finally subscribed to this site. I've visited several times to research or get advice. It's great, thanks to all. I purchased my 1970 2002 a few years ago as a project for my son and I. We were able to get it on the road (75% restored) and a daily driver for his 16th birthday. He drove it for a year and long story short is his mother wanted him to drive something more dependable and safe (with air bags ETC,) so I just recently got her back. My next project was to diagnose the electrical problems but, before I could the electrical system went haywire. Again, i'm new so I hope this is the right forum to ask, if not just point me in the right direction.
Old problem; I've gone through 3 electrical fuel pumps in a year. It's what came in it except I relocated to the trunk due to a vapor lock issue. I suspected a problem in the electrical system but, I just know the basics. I've tested the voltage to the pump and it sometimes reads 14.5 volts and drops to 12.5+ - with the engine running. I've replaced the voltage regulator and upgraded the wiring to the pump, no help.
New problem: I went out to start her and nothing. I did my normal checks, battery's good etc, but here's the weird thing (totally new). When I turn the key the tach jumps, fuel gauge drops and the stereo dies to the point the presets go back to factory settings, sometimes the headlight come on other times they won't. I really stumped......could this be a ballast resistor or coil issue?