trevorsmith82

non third gen carb here i have a 79 camaro 305 2 brl dual jet 210
i adjusted the choke the other day cause of the weather change and it was fine until this morning it seems like my throttle is stuck open

ive been idling at 2k in park and 1k in drive im supposed to be idling at 500 in drive
you crank it up and it idles normal until you give it gas and thats when it idles high ive tried to adjust the choke again and idle screws and still no luck

sprayed it down with carb cleaner no luck the throttle is just wide open
could it be the pump
just any thoughts ive never worked around carbs before
thanks for any help or ideas

Damon

Like the QJet, the DualJet has a choke system that both closes the choke plate AND advances the throttle when the engine is cold. If it's not heating up (opening) like it should it will stay on the advanced throttle (fast idle cam) even when the motor is fully warmed up. That is the #1 area to look at when you have a Qjet or DualJet that won't idle down.

If it's electrically heated, not having a full 12V to the choke element is a common reason. Followed by the choke element itself just being shot and not heating up like it should.

12V you can test for at the choke's electrical connection, obviously. Choke element is harder to bench test, but when it's overnight cold it should have a resistance to ground of no more than about 20 Ohms. If it's significantly higher than that, it's shot.

trevorsmith82

yeah i have the air choke the engine warms up to operating temps and it still does it ive filded around the choke a little today and no luck should i look into replacing the choke
i can get one dirt cheap new from autozone with my 20% discount or get a manuel conversion kit?

Damon

Not sure that will help. If the choke closes when the engine is cold and opens when the engine is warm, it's doing it's job.

Any chance the throttle shaft bushings are just so worn out it's hanging the throttle partially open when it tries to return to curb idle? The GM arrangement with both the throttle cable and the return spring going rearwards of the throttle arm is notorious for wearing out the throttle shaft/bushings. A tell-tale sign of this is if the throttle will return to the curb idle screw when the engine is not running but will "hang" slightly off it when it's running (engine vacuum is exerting force on the throttle shaft)

Or... you may just have a big 'ol vacuum leak somewhere (PCV hose, power brake hose, etc).

trevorsmith82

thanks damon for your advice
i checked the brake booster line by dscounting it and plugging it
i smoked the vacuum lines to find a leak and nothing

turned out to be a grounded wire that goes to the device on the carb thats infront of the throttle linkage no idea what its called so it was holding the throttle open

once i fixed the grounded wire everything was to normal

Damon

I think that's the A/C compensator solenoid (advances the throttle slightly when you switch the A/C on).

Or it could be the anti-dieseling solenoid that done effectively the opposite thing- it stays on (throttle advanced) any time the engine is running and off (throttle closed) when you shut off the engine to prevent dieseling/run-on when shut it down.

Those are the two most common applications for that throttle solenoid. Not sure which of those it was designed to do on your particular car/engine.