5ktq electrical problems update (not fixed)

[Doyt W. Echelberger]

FACT: When you messed around with the alternator wiring, it ran good after
running bad. Might be associated, might not.

HYPOTHESIS: Broken wire in the alternator wiring, or in the connector right
at the alternator.  Moving the wire re-established a better connection
between the broken ends inside the insulation, but then vibration of
driving degraded that temporary condition.

EXPERIMENT: Test this hypothesis by replacing the wires that you messed
around with. That way, you are sure to get the one with the broken segment,
if such a condition exists.

I also suspect corrosion in the connection of the central high voltage wire
that runs between the coil and the dizzy. Pull both ends and look for green
crud.

Doyt


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At 09:15 AM 9/23/2003 -0400, you wrote:
>This is a multi-part message in MIME format.
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>I'm still having electrical issues on the new '87 5ktq. The problem is
>that when ever the voltage gets to 12.8v I get a missfire, and 12.6v
>basically shuts off the motor unless I hold it full throttle. Normal
>voltage is in the 13.5 area. Problem is completely ignition related for
>sure. The voltage usually goes down to that range with the headlights
>and/or with the rad fan on. No, I can't just take the fan out and not use
>the headlights, :-).
>
>I have replaced the voltage regulator (yesterday, Eric's suggestion), and
>last night I found corrosion on the main engine ground, so I cleaned all
>of the connections there and cleaned the chassis where it bolts up and
>even used a new bolt. Didn't make a slight difference. Then I went to the
>alternator. I took both wires off and cleaned them, then started the car
>up and it was fine. I could use the headlights, even the highbeams, so I
>went for a 20 minute drive. It would still miss just slightly with the rad
>fan AND the highbeams on, but that's about it. So I went back to the shop
>to get my tuning computer because I was way rich on the EFI (on purpose).
>Went to go for another drive with the tuner and it was back to the same
>thing as before.



>I assumed there had to be something loose near the alternator, so I went
>to the starter and cleaned all the wires and contacts. I didn't have the
>chance to test it after cleaning the starter wires, but does this at least
>sound like I'm the right track?



>I did order a new ignition switch too, figured it couldn't help. I should
>be able to test it later today and install the ignition switch. I'll let
>you know what happens.
>
>My issue though is that ok with all of the charging system good I
>shouldn't ever go below 13v which would cure it, but shouldn't the
>ignition work fine well below 13v? Even if cleaning all the contacts get
>the charging voltage up to 14v it will fix my immediate problem, but I
>will still have weak ignition and loose power. I don't have the 2nd volume
>of the Bentley which is electrical stuff, so I don't have any wiring
>diagrams. I do get full battery voltage @ the coil.
>
>-Cody Forbes
>Black Forest Racing
>2x '86 5ktq
>'87 5ktq
>'88 80 4cyl
>
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