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rough idle

3726 Views 6 Replies 5 Participants Last post by  gawdzilla, 
8
ive got an 84 chevy pickup. quadrajet. right now im getting a quadrajet rebuilt to be put on my truck. on the old carb, it would idle really inconsistent. sounded like a big cam. ive heard its a vacuum leak, fuel mix, or maybe a shot carb. ive got new plugs and wires. it used to be that it would smooth out when it got warm, but not anymore. it sucks gas horribly like this. it'll smoothen out at very high rpms. does anyone have suggestions? thanks.
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Sir Joab
It sounds like your idle mixture is too rich, either that or your choke is sticking. A sticking choke would explain why the engine used to run fine once it was warm. If the problem was a vaccume leak the engine would be idling extra fast. (I used to have a vaccume leak on my Chrysler. Actually, I used to have a sticking choke too. :rolleyes: )

Joe
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Gokussj5okazu
Hey, I too have an 84' Chevy, had some of the same problems too. :thumbup: If it has the origional vacume lines check them out, they crack pretty bad. Check that choke, mine stuck for a while and was impossible to get it to idle. That QJet probably has the caps on the mixture screws so it's best to run through everything else before taking the carb off to remove those. Best of luck!
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1984chevrolet said:
ive got an 84 chevy pickup. quadrajet. right now im getting a quadrajet rebuilt to be put on my truck. on the old carb, it would idle really inconsistent. sounded like a big cam. ive heard its a vacuum leak, fuel mix, or maybe a shot carb. ive got new plugs and wires. it used to be that it would smooth out when it got warm, but not anymore. it sucks gas horribly like this. it'll smoothen out at very high rpms. does anyone have suggestions? thanks.
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Check your intake bolts. Did you replace the cap and rotor? If it got worse after you changed the plugs and wires, double check the firing order. Do a hot compression test to see if you have any weak cylinders.
Vacuum leak test methods
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8
im pretty sure its carb related. cap n rotor are next on my parts list. there is a lil bracket on the passenger side of the carb. it kicks up when stepping on the gas. this causes the rough idle. i can easily push it back down and this fixes it...well it used to fix it. thanks for the advice...keep it coming though.
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Gokussj5okazu
Ahh I had the exact same problem about a month ago, it really ticked me off too. I assume it has electric choke? If so try adjusting it counter-clockwise a bit. I had to move mine back about 10*. Normally you should be able to mash the pedal down after it has started to kick the choke and high-idle off.
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G
get a vacuum gauge and hook it up. How the needle fluctuates will help you decide if you're running rich/lean/or have a vac leak.
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