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Old 02-10-2009, 12:31 AM   #1
texanidiot25
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Carb loves to stay on fast idle

I have some mystery Q-Jet. Most of the choke parts were missing, but we figured it might be one that actuates on a temp sensor in the manifold. But to get it on the road we put on a manual choke cable. Not ever driving it before, dunno if that affected it, but now when driving around, when I left off the throttle the carb stays on the lowest fast idle speed setting. Right now I just tap the gas as I'm slowing down and this knocks it down to normal idle, but it's still an annoyance.

Anyway to fix this? Gets annoying when I forget to tap it off the fast idle when I shut it down and it knocks a few times more after I turn off the ignition (presumably because the motor is still spinning enough to fire a time or two more)
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Old 02-10-2009, 07:02 PM   #2
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Re: Carb loves to stay on fast idle

Ttt...
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Old 02-10-2009, 07:46 PM   #3
thirdstreettito
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Re: Carb loves to stay on fast idle

On the front of the Q-jet there should is a screw at the bottom IIRC, it is the idle controller. Twist it while the truck is idling and it will adjust the idle. I hope I remembered it correctly.
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Old 02-10-2009, 07:48 PM   #4
texanidiot25
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Re: Carb loves to stay on fast idle

I don't have a problem with my normal idle speed, it's the carb's fast idle mode for when you do cold starts, with the choke.. It has a few different fast idle speeds in the carb, 2-3 different "steps". It's constantly getting stuck on the lowest of the fast idle speeds while driving. To get down to normal idle (so I'm not wasting what ever amount of gas and vibrating the crap out of everyone's ears) I have to tap the gas hard as I'm slowing down or at a stop.

My idle screw is backed out all the way anyways.

Last edited by texanidiot25; 02-10-2009 at 07:50 PM.
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Old 02-11-2009, 06:53 PM   #5
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Re: Carb loves to stay on fast idle

ttt
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Old 02-11-2009, 07:12 PM   #6
Palf70Step
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Re: Carb loves to stay on fast idle

Maybe you need a stronger return spring. Also, it could be the rod is binding a bit at that point. Lubricate the linkage joints. I don't remember all the details of a Q-jet, I have not had one in years. But I have had the problem you mention and on more than one occassion the above fixed the issue.
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Old 02-11-2009, 07:17 PM   #7
dwcsr
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Re: Carb loves to stay on fast idle

Sounds like the missing parts from the choke are the issue. You still ned all of them and the choke pull off for it to work correctly. I have a Qjet that is complete with a busted flange plate, you can scavange it for parts if you want.
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Old 02-11-2009, 07:22 PM   #8
texanidiot25
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Re: Carb loves to stay on fast idle

I'll gladly take you up on that offer. I'll mention it to my dad tonight when I talk to him.

Do you know someone who has a good usable in-cab gas tank in our area as well?

Last edited by texanidiot25; 02-11-2009 at 07:23 PM.
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Old 02-12-2009, 12:27 AM   #9
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Re: Carb loves to stay on fast idle

Sent you a PM
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Old 02-12-2009, 10:16 AM   #10
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Re: Carb loves to stay on fast idle

I have the same setup, and had the same problem. I increased the spring tension on the secondary, and lubed the likage. This also took care of the bog down at take off. After doing this I had to adjust the fast idle screw down 1/4 turn. The spring adjustment is at the upper linkage of the cutoff. allen set screw aims down and small screw behind linkage adjusts tension. Fast idle screw is buried under vac cut off. Hope this works for you.
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