EDIT: 72+ views and not a single suggestion? Come on guys if you any ideas, any at all, no matter how unlikely you think it may be, please share!
I apologize for the long post, but this issue took a bit of explaining. Those that take the time to read this and give me some ideas, thank you!!
So I bought this 93 Accord coupe 5-speed last week, and it ran perfect for the first 50 miles or so. The tachometer in the car only ever read at idle with the car running, and the needle would actually move down a little as the RPMs increased. Right after I bought it, I replaced the ignitor and checked that the ground on the thermostat housing was attached and there was no change in the tach behavior. I was driving on the freeway yesterday when all of a sudden the tach jumped up and started working, and the dash lights brightened, then a few seconds later the tachometer and the speedometer both dropped to 0, then jumped back up to reading again then dropped back to 0 and the car shut off. Now there seems to be no power at all, no headlights or anything. Also, after the first time the tach started working and before it died it seemed like it was running on 3 cylinders. I was able to roll off the freeway and into a parking lot, but couldn't restart the car. I thought it was probably some kind of wire short in the engine harness, so I pulled the entire harness yesterday and didn't see anything melted or any damage. I pulled the loom off of all the distributor wiring thinking that was where the short would be, because of how the tach had behaved prior to the engine dying, and the fact that it seemed like it was misfiring (weak spark?) But all the wiring was good. Also had the alternator bench tested because someone suggested that, and it tested good. Ran out of light yesterday. Had to leave the car last night in the parking lot 15 miles away from home. Was able to set the alarm with the harness out so the alarm at least is getting power.. also no fuses were blown. I'll be going this morning to finish putting the harness back on but I'm not sure what to look at next. Please, any ideas, help or direction would be greatly appreciated!

 

I just thought of something...might the ECU have fried itself and caused these type of problems? And is there a procedure I can do to test the ECU with a multimeter? (Perhaps like testing resistance between specific pins on the ECU, like bench testing a coil?)

 

I had a similar problem on my prelude..weird tachometer...blogging..run great..turned out to be the alternator connector..tightened it and never had another problem

 

Okay, you asked for a wild guess, ...

It seems to be a wiring issue.
Yeah, I know you said you checked the harness
But, can never know .. vibration, flexing, shorting and then not shorting
Hopefully when you put it back in, the engine will start up again

 

If you turn the key to the 'on' position, do you get a solid CEL?

 

good point...