Primary Throttle Shaft Bushing Question

Old March 10th, 2019, 12:07 PM
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Primary Throttle Shaft Bushing Question

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Quadrajet feels like something is stuck when I step on the gas at start up. Once I pump the throttle a few times it feels freed up. It will remain free until I let the car sit overnight and then it does the same thing. I've replaced the throttle cable with a new smooth moving part.
Could this be the primary throttle bushings worn out? I haven't had this in any other vehicle before.
This was happening before my winter storage and now that spring is almost upon us I should get it worked out.
Thanks, Ben
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Old March 10th, 2019, 09:35 PM
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Can't say for sure, maybe the accelerator pump? After an overnight sit remove the air cleaner and use a flat blade screwdriver to depress the accelerator pump plunger shaft that sticks up through the hole in the carb. If it depresses smoothly the problem may be throttle shaft or choke related. If the accelerator pump is sticking the carb may need a rebuild. Good luck.
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Old March 11th, 2019, 07:18 AM
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You'll probably have to poke around and see what's hanging up.
I've had seals on the accelerator pump cause problems, had a slightly warped secondary shaft, misaligned throttle blades.... all kinds of stuff. Could even be the throttle cable or something with the choke.

The primary shaft problem is that the bores wear out, causing a vacuum leak. Sticking isn't common. So while bushing the primary plate is a good idea, I wouldn't do that first.
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Old March 11th, 2019, 10:18 AM
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Agreed, you need to investigate it more. My first guess would be the accel pump cup. You can see that carb has been "rebuilt", because there's a plug in the hole where the power valve is. Even though they may have put a modern accel pump in it, some of those don't work well in short order. My second guess would be where the cable hooks up to the carb. In that area, there should be a soft ruber bushing and a hard nylon type bushing inside if it. The inner bushing often wears or falls out sometimes during assembly. Primary shaft problems would be far down my list.
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Old March 11th, 2019, 02:40 PM
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I have the same issue with my 71 quadrajet and determined it to be the accelerator pump. It sticks first time using it after sitting.
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Old March 17th, 2019, 12:54 PM
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Turns out to be a sticking accelerator pump plunger. One drop of oil cleared it right up.
Thanks for the suggestions everyone.
Ben
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Old March 17th, 2019, 02:35 PM
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Problem is, it will be back. You need to change the pump.
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