-----Original Message-----
From: Speedo79@aol.com <Speedo79@aol.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: 08 June 1999 22:35
Subject: '77 'B run on-update (longish)
>Listers,
>
>First off I would like to thank everyone who has lent their vast knowledge
>for me to try to cure this problem. This list is truly a wonderful thing!
>
>Now, back to business:
>I took some readings with my trusty Radio Shack
>Voltmeter/Ammeter/Ohmetter/Widget, and here are the readings:
>
>Resistance across coil: 1.6 ohms
>resistance of resister sitting next to the coil, bolted to the "black box":
>10.5 ohms
>(this should be the stock set up for this car, but I know the coil is not
>original)
>with ignition off, voltage of hot fuse in fuse block: 12.7v DC
>with engine @ 3000rpm taken at same hot fuse: 13.6v DC
>with ignition on, voltage of positive terminal of coil: 11.2v DC
> " negative terminal of coil: 10.5v
>DC
>(is it just me, or is this not right? Both voltages taken with black
>terminal of tester to good ground, and red on one poll of coil (electronic
>voltage meter does register negative voltage when terminals switched)).
You will get 'nonsense' readings with a voltmeter on the coil with the
engine running because the voltage/current is being switched on and off.
They also vary considerably between 12v coil/points ignition, 6v
coil/external ballast/points and systems with various electronic modules.
To measure instantaneous voltages you would need an oscilloscope.
>with car running, voltage of positive terminal of coil: 12.2v at idle, 9.4v
>when revved above 3000rpm (again this throws me, shouldn't it be more at
>speed rather than at idle?)
>with car running, voltage between terminals on the coil: 0.7v DC
>(this is with one lead from the tester to each terminal)
>voltage at coil + with ignition off, but car running on: 12.2v DC,
>only faltering once engine dies.
This one shows that the coil is being fed a full 12v when the ignition is
off, which is why the engine is still running. The misfire mentioned
earlier could be due to the anti-run on valve having opened and greatly
weakened the mixture (if it is that type, some seem to shut off the fuel
rather than open the inlet manifold).
>The engine starts and stops the same way whether I am in the seat or not (I
>know there is a sensor in the seat that is supposed to be tied into the
>seatbelt, and ignition via a box behind the radio, but I don't think it
works
>anymore [the seatbelt switch still works-buzzer and seat belt light come on
>when started with seatbelt off, and only the seatbelt light comes on when
>engine cranked with seatbelt on.]).
>
>Like I said before, the car runs well with plenty of power. I am running
87
>octane right now, the engine knocks slightly only when fully warm and under
>heavy load. I drove around for 1/2 hour today, and the car did not get
above
>"12 o'clock" on the temp gauge (normal). When I tried to shut it off, the
>engine runs on for 15-20 seconds before stalling on it's own.
>
>I thank you for all of your help and comments.
>Sincerely,
>Steve Sanchez
Try measuring the voltage at the white wire on the ignition relay with the
engine running, both before and after you switch off. You should see 12v+
with the ignition on, and I suspect you are seeing around 6v or so with it
off but with the engine still turning. This is probably due to the
alternator problem that Rich referred to, and unless the alternator fairies
have been in the night and swapped your original-type alternator for a
non-standard one probably means yours has developed a fault.
PaulH.
http://freespace.virgin.net/paul.hunt1/
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