Everything dies except the engine?
 

Hello all, I had an interesting experience recently. These days, I rarely get a chance to drive my 86 RX-7 GXL, but I was this past weekend at night. I nearly always have to jump start the car these days since the car will usually sit for a month or so between uses.

Well, I started driving on the highway, and to my surprise, the headlights, dash lights, everything started to dim. Glancing down at the voltage gage, I saw the reading falling rapidly from 12ish range down until the dash lights dimmed out so I couldn't see the gage anymore. Lights went completely out, (just the tiniest glimmer from my glovebox light).. but (!) the engine kept running fine! I was trying to remember how far to the next lighted spot on the dark road was to pull over with hopefully some safety, but power came back, and I drove on.

Then once more, maybe 60 or 120 seconds later, all electrical dimmed out again.... I could hear a faint beeping sound coming from somewhere.. and again the car kept running. I pulled over (way over, no lights!) just past an overpass, engine still running, and was getting out of the car to check wiring connections to the battery and the alternator (had a flashlight), but the lights/everything came back on on their own. All the wiring connections looked/felt snug. The lights stayed on, and I drove the rest of the trip (~30 minutes) without any further problems...

Battery is a little over 3 years old, and I replaced the alternator about 2 years ago... The thing that puzzles me is that the engine kept running. I would think that if my whole electrical system went out, that I'd lose spark and my fuel pump, and the car would stall (it didn't even run rough).

Just wondering if any gurus have any easy insights as to what failure/circumstance would keep the fuel pump and spark plugs powered while there wasn't enough voltage available elsewhere to power a tiny little glovebox bulb..

fuses maybe??? id check the fusible links, just replace em all, couldn't hurt anything and is probably a good idea if they are all original.

only other thing is its being mean to you because you neglect to drive it more than once a month!

multiple systems going at once doesn't seem like a "fuse" issue to me (could be wrong, though).. Unless somehow every light on the car (including turn signals) is running through a single fuse somewhere.. Also, it would be really strange for fuses to dim out/brown out.. I'd think a loose connection like what I'm interpretting you to be talking about would be a on/off thing..

I may just have to wait until I have time to study wiring diagrams.. thought somebody might know off the top of their heads.

Alternator, the engine takes a surprisingly little ammount of voltage to continue to operate while everything else hogs up the electricity. Same thing happened to me last week when my alternator took a crap on me.

Yep, my alt belt snapped a while back, I managed to drive about 15 minutes to the nearest canadian tire, stumbling and backfiring all the way there, (especially by a cyclist, that was fun :D) Oh, and every one of my lights was pretty much dead.