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87442lover 01-24-2004 04:02 PM

Q-Jet wont idle?!?
Hey, I finally got the chevy Q-jet back together and installed. The problem is that as soon as I turn the ignition it revs to about 3K RPM for around 5 seconds and then dies. I can't get it to idle and I cant get it to stop reving so much when I turn the key.

Has anybody else had this happen after a rebuild, and anybody got any idea of what is wrong?


Oh yeah, I checked the secondaries and they dont seem to be opening at idle or anything so that doesnt seem to be the problem. The choke is also pulled wide open as soon as the motor turns over because it revs so high and creates alot of instant vacuum.

84 monte carlo 305 HO.

reborn55 01-24-2004 09:23 PM

Sounds like you have got a big vacuum leak. are all your vacuum ports in use. large one in back to booster and a couple in front--one to the pcv valve. May be set to lean, metering rods stuck down in the jets, mixture control solenois not working. Would check for vacuum leak or wrong base gasket first.

badknuckles 01-24-2004 09:37 PM


87442lover 01-24-2004 10:25 PM

A vacuum leak causing THAT much of a reving problem though? I mean it sounds like someone has their foot mashed down on the pedal or something, but the throttle is still in idle setting. But I will check it tomorrow.

reborn55 01-25-2004 08:04 AM

make sure the choke unloader is not jammed holding the secondary throttle plate open a little bit./ meant to say the scondary throttle lock out can cause the secondary throttle plate to stick partially open. Will cause similar symptoms

Jmark 01-25-2004 11:01 AM

A vacuum leak will not cause the engine to rev that high unless there is a huge amount of excess fuel going into the engine too. If the carb is moderately rich, an air leak will cause a slight increase in idle speed. If the carb is on the lean side, a vac leak will cause the idle speed to decrease.

Check to make sure that the choke fast idle cam is not holding the idle up. The fast idle screw us down under the choke housing facing foward. If someone set the fast idle up too high with a wrong choke setting, then with the correct choke setting, the fast idle will be sky high.

Look down the secondaries and make sure the bottom butterflies are COMPLETELY closed.

Same with the primaries, look down and make sure they will close completely when the choke fast idle cam is pushed all the way down. If its NOT completely closed with the idle mix screw backed out and the choke cam down, find out why. Usually, its the fast idle screw adjustment.

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