Another Problem.... Why?!

Well, the problem is back.... on my 84 Caprice (305, 4bbl q-jet) its got a light hesitation, a lot of stumble, and I get the dark smoke out of the exhaust when i give it gas. I had this problem before, but I repleced the O2 sensor, and it fixed it all right away. I've also recently rebuilt the carb. Now 2 weeks later its back again. The check engine light comes on now and then at idle, and the only code I got was lean exhaust (code 44). Also, the car floods really easy when its warm (it'll start, then immediately die and take forever ta start back up again).So heres the problems outlined:
-Hesitation
-Very Bad Stumble
-Easily flooded when warm
-Code 44 (lean Exhaust)
-Dark smoke from exhaust on acceleration (& when giving the engine gas)

Does anybody have any idea what could be wrong? Thanks!

Dissemble the carb again and check your float, its possible that fuel is getting inside the float and causing it to be out of adjustment

You mean the float might be shot, and its absorbing fuel? I didn't replace it (now I regret it) I'll give it a shot next weekend, unfortunately its my everyday car and is needed this weekend. Thanks!

If you have the CCC carb (computer command control), you need to set your mixture control solenoid dwell. When not set correctly, this will create (sometimes severe) a hesitation, stumble condition on acceleration. You'll need the proper scan tool & carb tools to make this adjustment.
Also, there are 2 welch plugs under the fuel bowl that leak. This fuel will leak directly into the manifold. This will cause a rich condition, plus an extended crank condition in the morning. You need to "epoxy" over these plugs. JB Weld works good. Mixture control dwell that is not set correctly can cause all sorts of problems. Especially hesitation & stumble. Hope this helps.

Jim S.

This is about the leaky plugs I mentioned:
You know those little brass cup plugs in the secondary metering well of a Quadrajet? They tend to leak. Machined aluminum replacements with o-rings are available, and there are also thick rubber-like seals that fit tightly into the cavity in the carb base and press against the underside of the well.

More about the mixture control solenoid:

Now, suppose you're confronted with symptoms that point to a faulty air/fuel ratio. Do you start by breaking out the steel anti-tampering plug and twisting the mixture screw? Not if you're smart you don't. That factory setting is probably correct, and if you don't want to go through a lot of gyrations trying to get it back where it belongs, look into more likely causes of the condition. Clogged passages could be the problem, but you check for them in every carburetor you disassemble, right? That's nothing new, but electronic mixture control is, and it's easy to test. Providing you got the proper dwell readings during your initial check-out, the mixture control solenoid itself should be suspect. Proceed as follows:

Remove the solenoid from the air horn and take the rubber seal, retainer, and spacer off the end of the solenoid stem.
Attach a hand-operated vacuum pump to the solenoid stem, then connect a jumper wire between either electrical terminal and a 12 volt positive source. Hook another jumper between the second terminal and negative.
Apply 25 in. Hg. The factory info says to time the leak-down rate from 20 to 15 in. Hg., and that if it loses those five inches in less than five seconds to get a new solenoid. I hate to disagree with holy writ, but it's been my experience that perfectly good specimens leak down very quickly once the vacuum reaches 20, so I time them from 25 to 20, which they've all done in about five seconds.
Remove the jumper wires to de-energize the solenoid and watch the vacuum gauge. It should go to zero in less than one second. If it doesn't, it's sticking in the down position and should be replaced.
If the solenoid's okay, check the metering jet for looseness, damage, or dirt.

While I strenuously recommend against tampering with the mechanical mixture settings, there will be cases where all your testing brings you to the unfortunate but unavoidable conclusion that they must be changed (maybe somebody else has fooled with them), and there's only one way to do it right:

With the manifold side up, saw two parallel slots in the throttle body so that they meet the idle mixture screw plug.
Using a flat punch at a 45 degree angle, crack off the tab you've created in the casting, then break out the plug.
Turn the screw in until lightly seated (it has a "Double-D" head that can be turned by wedging a screwdriver in next to it, but it would make things easier if you either buy a special tool, or fabricate your own by partially flattening a piece of tubing or cutting a notch in the end of a 1/4 in. bolt), then back it out four turns.
Remove the screen from the vent stack in the air horn to get at the lean mixture screw (it too has a "Double-D" head, but smaller). Seat it, then back it out two and a half turns.
Mount the carb on the manifold, but don't connect the bowl vent line or the EGR and canister purge hoses. Instead, cap the ports on the carburetor. Plug the port that supplies vacuum to the air cleaner temperature sensor also.
Connect the + clip of a dwell meter to the mixture control solenoid's blue wire (slip a stiff wire into the back of the plug as a tap), and the - clip to ground. Set the meter for six cylinders. Hook up a tach too (use the brown distributor lead).
Run the engine until the coolant fan comes on.
Hold the rpm at 3,000, then watch your dwell meter while turning the lean mixture screw -- you want 35 deg. If it's too low, back the screw out, and vice versa. You'll get a reading drift of 5 deg. with occasional excursions to 15 deg., but you're looking for the average. If you can't get it right, the main metering circuit probably has a leak or restriction.
Let the engine return to idle, and adjust the idle mixture screw until you get an average dwell of 25 deg. while the coolant fan is off. Back the screw out to raise the reading.
As a check, unplug the mixture control solenoid connector while observing your tach. If rpm doesn't change by at least 50, the idle air bleed circuit is clogged or leaky.
Reconnect the M/C solenoid, run the engine back up to 3,000 rpm for a few seconds, then note dwell. It should average 35 deg. If not, reset the lean mixture screw, then the idle mixture screw. A little RTV will work fine to seal up the idle mix screw cavity.

Wow, thats a lot of information.... thank you very much. I'm saving everything you just posted, and I'll try it all as soon as I get a chance (I'll try this weekend, but its not looking good time wise) You really seem to know what you're talking about. I hope to discuss more in the future. Once again I'm very appreciatve, and thank you!

No Problem Pete!!

Jim S.

lol i had this problme on my 88 and tonigh ti jsut got done swapping on a 72 truck q jet on,

all better no more smoke and stumble and crap

had real fun connecting the 700r4 TV cable though...... that was interesting, and very custom but it works and i got it to where its adjusted right now but the cable is melted at the bracket so i will be replacing it soon, so i can fine tune adjust it so i dont risk hurting the tranny, 700r4 are real picky liek this with the cable adjustment,
heh

if you dont have smog testing/inspections then swap older carb on without the ESC crap, find one on a 3/4 or 1 ton truck or van, or from 79 older car or 1/2 ton truck

will work but gotta rig for 700r4 cable


good luck