I know there have been other posts roughly regarding engine hesitation. But, my car has started doing something odd, and I figured I would run it by you guys. I will try to give you as much information as I can.

The car is a 1972 cutlass with the original 350 and correct two-barrel carburetor. It has been running fine lately and has had no issues at all. Really a smooth driving car all-in-all.

The other day I hopped in it to go to the store. I noticed that when I accelerate. The engine will sound like it’s not running for about half a second and then continue to accelerate like nothing happened. It’s like you have to baby the gas pedal off of a red light or it will do that weird half second delay.

The car will do this at any speed. If I’m on the interstate (for example) cruising at 60 and push the gas pedal quickly to pass somebody, it will do this brief delay then continue to accelerate and drive like normal.

personally I think it sounds like the accelerator pump to me. But, I’m I’m not quite sure how to diagnose that.

Also, it’s bothering me that I’ve noticed a weird feeling in my gas pedal. It used to be smooth all the way through it’s travel. But, now I feel like it’s very smooth pushing it down a third of the way, then I hit this invisible wall where the gas pedals really stiff. And it’s at that point exactly, if I push past that stiff spot, the car will stutter for a second and then continue driving. It’s like there’s a wall on my gas pedal, and if I ever so gently push past that wall, like very slowly, I can get the car to accelerate all the way without any hesitation. To specify this feeling, my gas pedal is very smooth to push in. Then there’s a rough spot where I have to apply more pressure to continue accelerating, The car stutters for a second at this point, then the rest of the way all the way to me flooring it is smooth as butter.

honestly, carburetor issues aren’t really my expertise. But I’m hoping to learn something from this thread and maybe one of you guys can help me out.


Also I’ll include a picture of said carb.

 

First you need to determine whether it's the carb or the throttle linkage binding somewhere. Disconnect the throttle linkage from the carb and move each full travel. When you operate the carb throttle locking down into the carb you will see 2 solid streams of fuel pray in there as soon as you move the linkage. If not replace the accelerator pump.

 

I would disconnect the throttle cable from the carb, then check both the cable movement and the carb throttle movement. They both should move easily with no binding, so check to see if one has a rough spot.

 

The funny feeling in the accelerator is almost certainly the cable going bad. The braided stainless cable inside the sheath wears, and eventually individual wires in the braid will break and stick out. These dig into the inside of the plastic sheath. Eventually the throttle will stick.
Ask me how I know...

The hesitation may or may not be related to the cable. You need to fix the cable first, both to eliminate it as a cause, and more importantly so you don't have a stuck throttle. If the hesitation persists, the accelerator pump is likely worn, which probably means a carb rebuild.

 

Thank you guys for your help.

I have a carburetor rebuild kit. And I think I’m just going to rebuild it because honestly it’s time. I’m going to undo the throttle linkage and actuate the carburetor by hand to see if I feel any resistance in the carb operation.

to test the throttle, do I just on mount the cable from the carburetor and tap the gas pedal? Like when it’s not connected to the carburetor it should just freely move as I push the Accelerator, correct?

Last question, if I want to replace the throttle cable for good measure. Because it looks like a fairly easy task. Do I just get a standard throttle cable, because I see that most of them specify there for a four barrel. Is there a special cable for a two barrel or is it all the same part?

 

Yeah, I was going to say that your biggest problem will be finding a new cable for a 2bbl car. Unfortunately they are different.

Now, if you need an excuse to convert to a 4bbl...

 

OK, so this was driving me up the wall so I went down to the garage to check everything out.

for throttle cable unhooked from the carburetor is smooth as can be. Forward and backward it operates fine.

The pivoting piece on the carburetor is also smooth and not binding.

what is binding and beyond belief is this pivot in the picture below. This one thing has all of the resistance.

 

That is the pump lever, I'm going to assume its the accelerator pump that's giving you your issue.

 

The accelerator pump cup may have inverted/sealing edged rolled over.

Good luck!!!

 

The good news is it sounds as if a simple carb rebuild will cure your issue.

 

Yup, that's the lever that operates the accelerator pump, so both your issues are tied to that one problem. Easy fix with a rebuild.

 

The fuel pressure, is that at idle, sitting? Or have you checked it when trying to drive it? Big difference! A failing pump might put out good pressure when, essentially, deadheaded, but fizzle out when fuel is really required.