My friend's got a 1986 IROC (305 TPI auto), and this is what his car's been doing lately:

A few days ago he was driving around and suddenly his voltage shot up and then the car died. Although interior lights and headlights etc worked, the ignition circuit wouldn't come back on and the motor wouldn't crank over. He said he didn't spot the voltage spike on the voltmeter but the interior light became very bright and then the car died. The interior light stayed on though.

He says he's checked all his wiring and it's good. His alternator circuit between the battery and the alternator has been partially rewired because the original circuit burnt out when Autozone gave him the wrong alternator a year ago. We tried to match as many things as we could with my car's wiring and everything seemed to be the same, except for one wire which I'll describe later.

The major difference in his car and mine is that he does not have a serpentine belt setup. He's got ordinary V-belts on it, so the positions of the accessories are different. His alternator and AC compressor are in opposite positions - alternator on pass. side, AC compressor on driver's side. The alternator is different from mine too. It's much bigger.

Anyway, a check of the system revealed only one blown fuse, and absolutely nothing else. This is the fuse that's right next to the battery. It's a 20 amp one, and IIRC, it's on the power supply to the ECM. The wire that I mentioned earlier is an orange wire, 12 gauge i think, coming out of the harness above the pass. side valve cover. This wire is spliced into the ECM power supply wire after the fuse. Since it didn't match up with the wiring on my car, we disconnected it and tried to start the car again with a new fuse, except this time the ignition circuit didn't come on at all. I guess that orange wire supplies power to the ignition circuit, and it's been like that before the problem started.

The alternator's been checked by Autozone and it came out good. The battery's good too.

If the problem were in that orange wire then shouldn't it have blown the fuse as soon as the ignition was switched on? It only blows once the motor fires up. It used to happen after a few minutes of running before but now it blows within a few seconds. We got it running for like a minute once but it blew again as soon as we put the transmission in Drive.

My guess is that either the alternator is bad, the wiring harness is chaffed somewhere out of view and causes short circuits, or that orange wire is not wired right. I couldn't find the same wire spliced like that into the ECM power supply lead on my car.

To make matters worse, someone fed him a load of horsecrap that his car's got a 350 not a 305. We ran the VIN on his car and sure enough it's a 305 just like mine. The parts guy at Autozone, who claims to be an ex-cop, went to the extent of teling him that his car actually a cop car with the LT1 motor, nevermind that the LT1 was in only a handful of 6speed cars in '92 that were never sold.

He also says 305 parts never fit his motor. BTW, these are parts that go on the outside, like waterpump, alternator, AC compressor, starter, etc. He says he burnt up the 305 starter on his car. I do know that the L98 and LB9 are virtually identical on the outside, except for the injectors. How could 305 parts not work with his motor, I don't know. True, he may have the higher output alternator but what else?

What gives? We're out of options just about ready to rip everything up in there. Has anyone had any similar problems? What was the source of the problem and what did you do to fix it? Thanks in advance .

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'88 IROC 305 TPI
Freshly converted to 5 speed
Gutted airboxes
180 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel (gotta luv it)
Ram-air setup coming soon
Flowmaster muffler (puke)
Taylor SpiroPro wires
Accel cap and rotor
Ported plenum
Throttle body bypass
Kills: '94 Z28, Olds Aurora V8, bunch of Mustangs, T-birds, ricers, and others who assumed a 13 year-old car would be too slow.

 

http://www.deadbird.org/z/87tpi03.gif

*edit,,, I forgot I'm not done w/it yet

I started making some ECM wiring diagrams the other night to pass some time. This shows that the ECM on that fused orange wire (red arrow) has constant power from the battery.

While I've never had that sort of problem you've described abouve, the wiring would be suspect to me.

I'm sure you've seen the link but here is a good site showing the wiring diags for an 85 camaro

http://www.geocities.com/vtcamaro/Wire-Diagrams.html

Hopefully someone else can help you beyond that. I can only offer good luck in hunting down the wiring fault & some diagrams.

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[This message has been edited by deadbird (edited December 05, 2001).]

[This message has been edited by deadbird (edited December 07, 2001).]

 

ttt