Replies:
From
Bob:
I have experienced your problems
some years ago and will pass on to you some ideas to stop the problem.
My problems always occurred after some warm-up period. Upon cooling, it
would usually restart. It is my opinion that the fault is Ignition rather
than Fuel. During warm-up, when it stops, remove the Air Cleaner Cover
and have someone go thru the Start cycle, you should see some fuel squirting
from the Spray Bars. It's a good idea to have grounded the secondary wire
from the coil to the distributor prior to Start. Two tries may be necessary
to get the fuel to spray. Recycle the Ignition key to Off, then repeat.
If you get the fuel, proceed to Ignition tests. Remove the 10 Way connector
from the rear of the Computer, and connect an ohmmeter between connector
terminals 5 and 9; you should read 150 to 900 ohms. If yes, connect one
ohmmeter connector to a good ground, the other to connectors 5 and 9 alternately;
there should be no continuity; if there is, disconnect the Pick-Up Coil
connector at the Distributor and connect one lead of the ohmmeter to ground,
the other to each terminal, on the Distributor end of the connector, there
should be no continuity. If there is no continuity, check the wire from
the Computer to the Pick-Up Coil for a short to ground, this may be an
intermittent thing, so carefully trace the path and look for abraded insulation
on this wire. If there is continuity, replace the Pick-Up coil. Because
you cannot predict when this fault will occur, I have been able to warm
the Pick-Up coil with a hair dryer, while the ohmmeter is connected to
the two wires, and in less than ten minutes, under mild warming, the ohmmeter
will open and this will indicate that there is a problem within the Pick-Up
Coil - replace it. There were a bunch of 81's with this problem and it
was due to a bad production run of these coils.
From Dick:
I think I am the guilty party
for the suggestion about bypassing the ASD. Even though it did not make
your problem go away, the fact that doing so had no effect on the problem
adds to our knowledge about the situation. Now we know that failure of
power supplied to the fuel pumps or the EFI/CCC system is NOT the problem.
You can put that whole category of investigation on the back burner. If
the car stalls when it is just sitting there idling normally, with a good
strong steady idle, and then just dies on you, then restarts with no special
fiddling (please verify that this is indeed your symptom), I come around
to a suggestion Bob Harris made a while ago, namely a possible temperature
induced momentary failure in the distributor's pick up coil. I think we
talked about this possibility one time before. Did you replace the pickup
coil at that time? Bob suggested that if the pickup coil is suspect, one
could take a VOM and measure continuity from one wire to the other of
the 2 wire pickup coil connector ( it comes out of the side of the distributor,
unplug it and connect to the end which goes into the distributor), while
heating the coil assembly with a hair dryer. When the coil is OK, you
will see a quite low resistance (I forget the number at the moment, but
it would be no more than a few hundred ohms, probably much less) and when
the coil opens, you would see very large resistance, over 10,000 ohms
for sure. This is an easy test to make, and can be done without disturbing
any of the settings. I am not absolutely sure this will always identify
a failing part, however, perhaps Bob can shed some light on how foolproof
this test is. Personally, if I suspect this part, I just replace it with
a new one, since they are cheap and relatively easy to change, see procedure
below. They are available from NAPA, and possibly other parts sources.
You need to remove the reluctor magnet to get at the pickup coil to replace
it (it comes only as a complete assembly, already attached to the "breaker"
plate). I think it is a good idea to replace both pieces at the same time
(pickup coil and magnet), since they are cheap, and you might damage the
old magnet getting it off. If you decide to replace these parts yourself,
be advised that you will have less trouble in the long run if you pull
the distributor to work on it. There is only the one 2 wire coil connector
to deal with (after you get the rotor and cap out of your way), but of
course you will have to be careful to reinstall the distributor and rotor
in the same position that it was in when you removed it, and make sure
no one bumps the engine over while it is out, or else you will have to
go to plan B to find #1's TDC point. Then you will have to reset the timing
(12BTC at idle). Be very cautious when pulling the magnet off the end
of the shaft, if you put any more than a few pounds force on it, you can
easily damage the bottom thrust washer, which is pretty feeble. It would
be best to hold the shaft itself rather than the distributor body to pull
the magnet; this is difficult without removing the distributor. Even if
you do not disturb the distributor, you will also need to set the gap
from the tips of the 8 finned rotating magnet to the pole piece of the
pickup coil to .006 ", which will take a non-magnetic feeler gauge.
This will be hard to come by, I use a piece of .005" shim stock (brass)
and set the gap a little loose. I'd like to hear what Bob has to suggest
on this problem too, he has a world of experience with these cars and
their teething problems, and I gather this was not unheard of even when
the cars were new. I'll be quiet until I hear more.
