Peter,
I had the symptoms you describe many years ago and traced the problem to
a pin hole in one or both (been so long I don't remember which) in the
diaphragms). Check them very carefully by stretching them slightly while
holding them up to a strong light. Also make sure the seal is good
around them and the tab is in the recess.
HTH,
Jim Davis
Fortson, GA
CF38690UO
CF37325U
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Peter Zaborski
Sent: Monday, March 31, 2003 9:52 AM
To: 6 Pack (E-mail)
Subject: choke problem
Hi 6 Packers,
Sorry in advance for the long post :-).
I'm trying to diagnose a problem with my choke operation. Perhaps some
one can shed some light on this. Car is a 76 with the stock ZS carbs and
my emission plumbing is gone. Car has run fine with this et up before
and the choke used to work as well so I doubt it's the missing plumbing
but thought I'd throw that out anyway. Onto the problem...
My choke is not working as I would think it should. If I pull it out all
the way when the car is cold, the car will typically not start and if it
does, the idle is less than normal idle speed and eventually (ie. maybe
10
seconds) the car will die. I have to start with choke all the way in and
keep pressing the gas pedal to keep it idling until warmed up. Once
warm, if I pull the choke out it will kill the car in the same manner.
My understanding is that the first part of the choke cam action (ie.
until the detent in the cam contacts the spring and ball) richens the
mixture, and the second part of the action the cam contacts the screw to
the throttle lever and mechanically increases the idle speed. I am not
seeing this increase idle speed when the cam goes into that second range
(nor when it is in the first range).
I have attempted to tune the carbs following Nelson's directions on the
Buckeye site but am so far unable to fix this choke problem. After
tuning my normal drive way idle is around 850.
My plugs appear to be fine after a run. The front 3 are a nice tan
almost tobacco color. The back three slightly lighter but still
acceptable.
Some other facts:
- Car usually stumbles from a standing start until revs increase and it
gets going, then it seems to run fine. This stumbling occurs even when
fully warmed up. I am using Pertronix ignition and Magnecor wires FWIW.
- Once fully warmed up, like after a brief highway run, coming to a stop
will see the idle go to 1300-1500 and if I stay stopped long enough
(maybe 30 seconds to a minute) the idle will slowly return to almost
normal (around 900-950). I did re-set the temp compensators like
described in the VTR article and Nelson's site.
- The idle screw on the front carb needs to be less screwed in than the
rear after a tuning iteration in order for the Unisyn to show balance at
idle. I believe all my hoses are fine. Haven't checked the carbon
canister internals.
- I rebuilt the carbs a few years ago (maybe 3) and the car has run just
fine after that, including the choke. In fact in the 21 years I've owned
this car, this is the first problem ever with the choke.
- The anti-run-on valve operates normally. In ever get run on and it
does click after shut off.
My suspicions are that my mixture is too rich and thus the choke is
killing it by enriching even more. Although I'm not sure if this is even
possible by the amount of enriching the choke provides? If not, what
else could be causing the choke behavior?
And is it possible for the mixture to be too rich at idle only while
once running the mix goes to an acceptable level (as evidenced by the
appearance of the plugs)? I have not checked my plugs after merely
idling - is this worth while? I have access to a Gunson Colortune
mixture tuning kit it that might be worth using.
Any ideas would be greatly appreciated. Thanks!
Peter Zaborski -- CF58310 UO
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