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Old 05-14-2012, 11:35 AM
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Carburetor issues on 1981 Pontiac Trans Am 301ci.

Hello. I have an odd problem with a rebuilt carburetor I recently purchased. Here are the issues:
1) I cannot plug in one of the electrical plugs (top right, greenish color with three pins, on the original carb it was white) or the cars idle will fluctuate wildly. When I try to accelerate with it plugged in the car stalls almost to the point of dying out and sputters until getting to a fairly high speed.
2) With that disconnected, I can get the car to idle perfectly, and accelerate better. However it still does not accelerate correctly. If I accelerate slowly it makes a bit of noise and has very little power. And if I try to accelerate quickly, not only does it not have power, but it makes a loud popping noise and misses. The only thing I can figure is I am getting too much air and not enough gas.
3) When the engine is cold, it has a lot of trouble starting, it runs absolutely terribly, it stalls, shakes, misses, and makes the loud popping noise even under light acceleration until the engine warms up a bit.

The car is a 1981 Firebird Trans Am, 301ci 4.9L non turbo California model. Everything is stock. I have rechecked the timing, done a full tune up, checked for vacuum leaks, and a few other things. None of those are a problem. So in your opinion, why would the electronic connection cause this carb to act so erratically? And if I can get the carb to work correctly with that connection in, will it fix the other problems? I had none of these problems with my old carb, including the electronic plug. It worked just fine with my old carb. Could the air/fuel mixture need adjusting? Or possibly something else you can suggest? On a final note, the only thing different about this carburetor aside from the plug being green, is the base gasket it came with was open, and the old gasket was split three ways. I don't know that it is important, but I'm trying to give as much info as absolutely possible.

Thank you all in advance.

-Navarro

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Old 05-14-2012, 04:44 PM
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Post a couple photos of the connectors you are talking about.
Also the check engine light must be on, that is if it works.
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Old 05-14-2012, 08:03 PM
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Quote:
Originally Posted by NavarroZero
Hello. I have an odd problem with a rebuilt carburetor I recently purchased. Here are the issues:
1) I cannot plug in one of the electrical plugs (top right, greenish color with three pins, on the original carb it was white) or the cars idle will fluctuate wildly. When I try to accelerate with it plugged in the car stalls almost to the point of dying out and sputters until getting to a fairly high speed.
2) With that disconnected, I can get the car to idle perfectly, and accelerate better. However it still does not accelerate correctly. If I accelerate slowly it makes a bit of noise and has very little power. And if I try to accelerate quickly, not only does it not have power, but it makes a loud popping noise and misses. The only thing I can figure is I am getting too much air and not enough gas.
3) When the engine is cold, it has a lot of trouble starting, it runs absolutely terribly, it stalls, shakes, misses, and makes the loud popping noise even under light acceleration until the engine warms up a bit.

The car is a 1981 Firebird Trans Am, 301ci 4.9L non turbo California model. Everything is stock. I have rechecked the timing, done a full tune up, checked for vacuum leaks, and a few other things. None of those are a problem. So in your opinion, why would the electronic connection cause this carb to act so erratically? And if I can get the carb to work correctly with that connection in, will it fix the other problems? I had none of these problems with my old carb, including the electronic plug. It worked just fine with my old carb. Could the air/fuel mixture need adjusting? Or possibly something else you can suggest? On a final note, the only thing different about this carburetor aside from the plug being green, is the base gasket it came with was open, and the old gasket was split three ways. I don't know that it is important, but I'm trying to give as much info as absolutely possible.

Thank you all in advance.

-Navarro
I believe you're referring to the throttle position sensor (TPS) of the Quadrajet carb w/CCC emissions (Computer Command Control).

BTW, it's better to use "passenger" or "driver" side to indicate the position of parts on an engine unless you specify it's facing the engine (like you're using) or like it's traditionally done, from the driver position sitting in the car (which would make to TPS on the left, not right).

Getting back to the TPS, it has to be adjusted using a dwell meter. Instructions are online I'm sure. The other connector is for the mixture control solenoid; it has two pins vs. three pins for the TPS.

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Old 05-15-2012, 01:41 PM
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As mentioned, you need to adjust the TPS, and the idle mixture, choke setting, hot idle.

Rebuilt only means that someone replaced any broken/worn parts and gaskets, there probably was no adjustment done to the carb., you have to do all of that.
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