Primary Throttle Shaft Bushing Question
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Joined: Feb 2010
Posts: 400
From: Ontario
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
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
Registered User
Joined: Nov 2015
Posts: 685
From: So. Ca.
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.
Registered User
Joined: Sep 2011
Posts: 2,148
From: Plano, TX
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.
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.
Registered User
Joined: Jul 2010
Posts: 1,907
From: Toytown, MA
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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