Electrical fire after new battery installed and ground wire
 

well i have an '85 1st gen rx7 and it was running beautifully for like 4-5 months after i bought it. Then it started slowing down very rapidly like one day it was gettin to about 90mph with no problem. Then the next day i was gettin 60mph tops. The day after that it went about 50mph in the morning and by 4pm it was barely gettin to 20mph. I had a mechanic check it out and he said basically give it a tune-up and he found that the ground wire was missing completely. Well we switched out the spark plugs and wires, Put in a new battery, and hooked up a ground wire. Then we tried to start it and the wire harness by the battery caught fire. So ya thats pretty much what happened there. Anyone know what i can do about it? thanks.

Yes, fix the wiring or get a new mechanic. :-)

Sounds like maybe you grounded a power wire instead of adding a ground. Thats what would cause the fire. Or you installed the battery backwards.

aight ill look at everything and add a ground.
maybe i was just rushin too much and got somethin in wrong.
thank.

Ditto. what part of California are you in i know quite a few people down there. unfortunately one of the people i would of suggested passed away a year or so ago.

if i was still living down there i would offer to help you but Oregon a bit of a drive.

actually i live in north cali about an hour above Sacramento. Yuba city if youve heard of it. but ya thatd be great cuz noone i knows how to work on the rotary engines. thanks.

It has nothing to do with the rotary engine. And everything else on an FB is ultra conventional, which makes it easy and cheap to fix, which is one of the reasons us cheap and dumb guys love them (aside from the car looking sexy and handling great).

Sounds like you mis-wired the battery cables, possibly by putting the battery in backwards or by mis-applying that extra groundwire. While it is certainly true that an automobile (any automobile) must have good grounds, usually that means repairing a broken or erratic ground rather than adding a new one. Usually a bad ground is the result of some kind of improper electrical repair, like a starter or alternator replacement. But it could also be degeneration of the aluminum battery cables that were used in cars for a few years in those days. Sometimes oxidation of aluminum at compression connections can cause enough resistance to provoke heating up at the junction. That's why they quit using aluminum wire in house construction. Hell of a thing!

Most likely your original problem, the car slowing down in an alarmingly short period, was caused by the fuel filter gumming up. Or it might be that the old fuel pump is degenerating. I had exactly the same symptoms last year after driving more than an hour I had to creep home on a splendid freeway at 40mph while people whizzed by me shaking their heads at my folly in driving such an old car. I had the mechanic replace the fuel filter (always a good idea) and test the fuel pump pressure afterwards. The pressure was 10% below FSM spec, so we replaced it, thus restoring full pressure and eliminating the problem. Sometimes it pays to test before replacing parts.

What caught fire? Maybe the fusable links? Mine went up in a puff of smoke and flames, replaced them with a better fuse box and have not had a problem since, just a thought