Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Help with diagnosis for an '84 Trans Am

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qjetsrule:
check to make sure the choke is opening fully, if not make sure you are getting 12 volts to the choke coil and the connection is good. on the other end of the spectrum you might have and open vacuum source somewhere, a friend of mine uses a small propane torch ( not lit ) to locate vacuum leaks, works good and no mess. good luck

jamesF:
Is it anytime you apply the brakes or only as you are driving at speed then come to a stop?
Could be flooding due to fuel sloshing?

TO see if you have a vacuum leak like qjetsrule mentioned you can use one of those handheld Propane torches. Open the valve a little bit DONT LIGHT IT OF COURSE, then move it around the carb base as you are idling. The propane acts like fuel and if there is a leak that is sucking in air, the car will speed up. If that happens look and see what the deal is in that area.

Now if the air cleaner is off sometimes you can get false readings if the fumes get pulled in the top inadvertently. So hold it down near the base as you move it around. This is where the leaks would likely be anyhow. You can also spray carb cleaner (I think its still made out of flammable solutions) sometimes the little red straw will help you be more precise... It also cleans the engine!!  ;)

jamesF:

--- Quote from: qjetsrule on March 17, 2011, 10:15:41 PM ---check to make sure the choke is opening fully, if not make sure you are getting 12 volts to the choke coil and the connection is good.
--- End quote ---
Amen.

Funny thing happened to me a few months back, I have my electric choke getting power from a splice in the wiper motor power. I was doing some work in the interior during my final "resto repairs" work, putting my wiring back together in the car, and shorted something and blew a fuse. Stuff stopped working, etc.. I looked and didnt have any fuses, got my keys and went to start my car to go buy some fuses and it idled REALLY BADLY... This was  shortly after putting my newly rebuilt 455 I had built in the car that had been very consistent in sound and idle and running quality..... I started to sweat thinking bad things...
Realized my choke was not getting power due to the blown fuse....
Whew.....

shelivedhere:
Thanks so much for all the responses.  There's a ton of good info here. I'm also wondering if using something like Seafoam in my gas tank might help things. Is it possible that the carb just needs a good cleaning?  I've been noticing that the idle has been a little smoother and the stalling hasn't been happening as frequently since I had the O2 sensor replaced two weeks ago.  I've been driving the car more often and been taking it on longer trips.  My immediate concern is that I need to get it to pass CA Smog Testing in the next few weeks and I don't know how all this is going to impact my chances of passing.

I also just found out that the shop I take my Honda to handles this type of thing so I think I may have their mechanics take a look at it given my time constraints. But I will make sure they check all the things you guys mentioned. Thanks again for the guidance! I will keep you posted on the progress.

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