First i would like to say hello to the site since i'm new here, it looks like a great one.

I have a problem with my car stumbling from a dead stop or at idle ,when i hit the pedel it "gulps" and stalls or almost stalls out and then it picks up.
Is this a bad excelerator pump, there are no adjustments on the arm for the pump to change the amount of gas like i have seen on some other carbs with about three holes on the arm.
Do i need to completely rebuild this carb.
What can i do.
thanks.

 

Welcome aboard.

Are we talking about a stock quadrajet? Are you talking about going to wide open throttle? If so, you probably have the famous "q-jet bog", which is a secondary air valve adjustment issue, not an accelerator pump issue.

If you are talking about "normal" driving pedal depression, then it could be accelerator pump, or an ignition problem. You can watch the acclelerator pump shot with the air cleaner off and engine shut off, it should give a squirt as soon as you move the throttle. If the timing isn't set right, you can get the symptoms you describe.

 

After the car has been sitting over night the gas pedal has to be pumped to get enough gas into the engine to start, if the first time of the day it's pressed there is no gas squirting out till a couple more times.

After the car is running and at idle if the pedel is pressed down quickly and let off it will stumble and probably die unless the pedal is " feathered" to keep it running.
While the car is driven down the street if the pedal is pressed to the floor it will bog down and die unless i either ease into the gas or feather it again to keep it running.
This is a stock carb.
Is that enough info to help describe the problem.

 

Mine does that too, after I just rebuilt mine. Is your choke set up right?

 

it does it even after the car is warmed up and the choke is off.

 

Do you get enough gas while cruising? Does this just occur pulling away from a stop?

Maybe not getting enough fuel-bad pump, clogged filter?

 

While cruising it runs fine as long as i don't have to floor the pedal.

Even after driving for a long time if i floor the pedal it will fall on it's nose and die unless i feather the gas pedal to keep it running.

So is this a acc. pump problem or secondarie adjustment problem?

 

is there any chance the problem is,
too much accelerator pump and-or too rich idle ?

just for fun, you might try ,
disconnect the accelerator pump linkage,
and tell us what happens.

or

does the problem get better or worse,
if you make the idle mixture leaner?,
get as lean as possible - that allows car to run.

 

i know this post is a few months old, but i was having the same issue. i thought it was a vac leak causing the bog due to some probs with the rear seal on my stock intake and others with the carb. i recently installed a *new* rebuilt cc q-jet and an action plus manifold and bog was still there.

i adjusted the sec. a/v first using the instructions in "how to tune your cc q-jet" on this site, i adjusted it to the least tension just before the a/v flops open by itself, the bog was still there.

i happened to have a secondary metering "B" hanger which i just swapped in today, i don't remember which metering rods are in, but i know they have a "power tip". my bog seems to be gone, i've been driving the car hard almost all day and went through about 1/2 tank of gas. i tested WOT from a dead stop, slow roll, around a few corners ... cruising a straightaway, no bog yet.

i have just one concern right now, and that is i don't want to cause cylinder wash by running too rich. the 'ol LG4 is pretty much stock, no cam etc. i've been running 91 octane, it would ping up hills on 87. my base timing is set 6 deg. adv., mentioned the "B" hanger and a/v setup ....

any way to tell if its too rich without digging up $$ for an air/fuel gauge? i really dont have any spare cash at the moment for one. or should i tension up the air valve a bit and go back to my "J" hanger?

p.s. sorry, not trying to hi-jack the thread. i appreciate any feedback guys.

 

An A/F gauge will not help you tune a carb at all. Believe me. Dont waste your money.

Definately tighten the AV up a bit. I have mine adjusted well, and it's about.. I dont know. Just tighten it. As for your hanger, I would leave it, but see what rods you have in it. If they are much richer than DR, I would change them back.

 

the rods that are in it are CK rods... the only other rods i have are CH. i originally had a J hanger and CH rods ... the new carb came with a B hanger and CK rods. those are the only 2 sets i have. i've tried the following combo's with them:

Hanger / Rod
B / CH
B / CK
J / CH
J / CK

and that is pretty much all i can do for rod & hanger combo's right now. the B/CK combo *feels* the best. as far as washing the cylinders with fuel, what are the chances? if the a/v is open too much then it should be leaner shouldn't it , due to more air than fuel? i just want to get a good mixture going so it's nice to drive and won't bog. this is my first time trying to tune a carb so any help is greatly appreciated. thanks

 

well, i tightened the a/v up approx. 1/8th of a turn ... then 2/8th's, then 3/8th's , and then went back 1/8th. it felt best there and i haven't felt a bog yet. cool. thanks ta86