I have an '83 z28 305w/quadrajet. The choke light is staying on and the car will not idol on its own. What is the deal? It will start right up everytime, but take the foot off the gas and it dies. thanks guys

 

um? obviously the choke is stuck.. open the hood and take air cleaner off (if equipped) and unpluge wire that leads to choke and put a clothes pin in the choke and try to start it. i bet it works..

 

Well it starts right up thats not the problem. It just wont stay running without giving the gas.

 

These have an electric choke which have a tendency to short and/or burn up. You need to check the system; fuse, resister, relay, and changeout whats bad.

 

Mine also used to do the same thing. My O2 sensor is shot.. but even after i got the carb working the O2 was still shot the carb was just running full-rich. BUT.. try spraying some Carb cleaner into the carb, and all around. Pretty much just layer everything. I also changed my fuel filter. Unplug the elec. choke and try it.

 

The choke light on these older cars is tied in with stuff you can't even believe it's tied in with. Like what? Well, like the oil pressure switch and the alternator. Most likely it actually IS the choke that's the problem, but have your alternator tested at a local parts place just to be sure (please don't make me explain, just trust me and do it, OK?)

The only function that the idiot light can actually monitor on the choke is it's electrical resistance. It has no idea if the choke is actually open or closed. Unplug the wire from the choke element (round black thing on the pass. side of the carb). Measure resistance between the terminal on the choke element and a good ground (the main body of the carb). Should only be 5-10 ohms. If it's up over 20 the element is shot and needs to be replaced.

To check the function of the power supply system to the choke measure the voltage going to the choke element with the engine running. Do this with the power supply wire hooked up live to the choke element as it normally would be. You'll have to probe in there carefully to catch the terminal with the connector plugged onto it. It should be getting a full 12V at the terminal with the engine running. If not, you got a weak power supply to the choke (probably the relay or a bad wire).

I am honestly only scrathing the surface of the issue here. It's a DAMNED complicated circuit and having a factory shop manual to reference is a REALLY good idea. It can provide you with diagnostic trees that are invaluable in tracking down the real problem on this very quirky circuit.

 

having dealt with the choke on my '82 quadrajet, i can tell you that these carbs are less than reliable, and after 20 years of use, is probably spent, causing the choke to stay on. the basic principal of the choke is that when the carb housing is cold, a heat sensitive valve closes the top butterfly flap, bloking out all air from the primaries (which are on when car is idling), causing an extremelly rich mixture to help warm up the car. however, when the car is warm and the choke sticks on, the motor is unable to get the amout of air it needs to stay running, causing stalling and poor idle. a new choke and housing will retail at a shop for as much as $500, so in reality, the best choice is to but a new carb with electric choke. a holley 600 cfm is probably plenty of carb for your car, and will have electric choke, vacuum secondaries and retails for about $280 at advance auto or auto zone. i have one of these installed on my car, and it reacts very well to mild engine mods. they are very easy to install and tune, and will work perfectly through the winter no mater where you are (i live in laramie wyoming, elevation 7200, and i never have a problem). good luck

 

$500?!?!?!?!

No way. I replace the choke elements on these carbs all the time. A new electric choke element, if you actually need one, will run you $40 at the local auto parts place. Drill out the rivets that hold the old element in place, pop it out, put the new one in and screw it in place with the supplied self-tapping screws. 30 minute job.

Also, you can't easily replace the QJet with anything but another QJet. Not jsut becuase it's computer controlled but because the stock manifold is designed to ONLY take a QJet. Using Holley -> Qjet adapters doesn't work very well with the stock manifold.

 

Damon, I hear you on the Alternator thing. My old 86 did the rerverse once. Choke got stuck and the car would not come down off fast idle in the morning. I had to rig up something to keep the choke down. Turned out my alternator was bad. The regulator was fried and the signal was going through some mess of relays and what not, something that the two shared in common. Swapped alts and it went away instantly

Will

 

I had that problem. it turned out to be my alt. although i did have problems with my carb and electronic choke it did not turn on the choke light. getting an alt is a lot cheaper than getting carb work done. "get that alt checked" is just my humble, maybe wrong opinion.

 

i posted a response a few days ago and was mis-quoted, $500 is for the entire choke setup at a shop including labor, not just a measly filament. these carbs are finicky, and rarely are just as simple as a filament. i you are lucky, thats all it will be, but i sounds to me like more than that. try the cheap fix first, if it comes to the worst, just replace the carb. you'll get better performance and reliability anyway and won't ever have to worry about the choke again.

and using an adapter plate with a stock manifold works fine, i did it for 3 years in laramie wyoming with extreme winters without a problem, it will even clear your stock hood. just an extra 15 bucks and four more bolts. dont feel trapped into staying with a q-jet because thats whats already on your car. go with what you think will work best.

 

Ok, I replaced the alt which was bad and sprayed her down with gumout carb cleaner. The car seems to run a little better now but not perfect. The choke light is still on. What is the next step I should take besides going to the shop.
HINT: I am not a mechanic but I can work a wrench! Thanks all.

 

Most ARE just the choke coil, and not the whole setup. Who quoted you $500 for a choke repair? You can buy a completely rebuilt QJet from several companies for hundreds less, with a properly functioning choke.

Damon knows these carbs well, and pointed me in the right direction several years ago when I had some carb issues. Diagnosing problems over a message board is no easy feat, and he accomplished it quite easily. I've since taken the ball in my court, and have helped a few friends and coworkers with their QJets (almost exclusively CC Qjets). Once you "unlearn" what you know about other carbs they are not that difficult to work with.

 

i have a few questions,
Does the throttle position thing have any thing to do with the Cruise Control? What runs cruise control? and the other wire on top blue green plug thing? whats that for? If i were to get a edelbrock 600CFM carb what would happen if i didnt hook those wires up? Or if i got a rebuilt 68 Q-jet? I have a 68 Q-jet 4bbl, Nothing wrong with it.. it ran the 68 350 ss i just put in my camaro.. i have the old 305 carb that came with my camaro when i got it, but i think its junk..? I am still putting my engine back together. So dont quite know yet..