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high idle quadrajet

Old 04-03-2010, 07:08 PM
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high idle quadrajet

ok so i went and bought another quadrajet that was "rebuilt" well i put it on and just blew gas all over the place, so im guessing its clogged somewhere, because all the springs are corroded and the bowls are filled with some rust crap

anyways, the point is, i put my old one back on, because i need it running. when i started it up, it was idling 200 rpm faster than it usually is, at about 1000 rpm, i went about 14 miles and didnt touch the gas pedal for the majority of the trip home, when stopping at a red light the idle didnt lower at all, and at this point the rpm has risen from 1000 to 1200 while the break was applied in drive, when i got home and put it in park, the rpms jumped up to about 2000, ive been wrong before, but that does not seem right to me, lol

i did not touch any of the adjustment screws, so unless i accidentally bumped an adjustment screw while taking it off and putting it back on, i would assume that it would run the same as it did before

another thing, i went to the store a little bit ago and the idle seems normal now, but its running a little rougher than before

also, i can smell gas pretty strong after shutting the engine off, so that just makes me think im running rich now too

i know something is wrong

does anybody know what is going on, or give me something to go on, i dont know a whole lot about quadrajets

thanks
Old 04-04-2010, 06:16 AM
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Re: high idle quadrajet

Did you remember to reattach the power wite to the choke element on the pass. side? If the choke isn't opening fully it will hang on the last step of the fast idle cam (which is built into the choke linkage) and idle high when warmed up.
Old 04-04-2010, 11:11 AM
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Re: high idle quadrajet

thanks for the reply

thats what i dont get, the "new" carb i was putting on has a choke and all the pieces, and its the exact model and year as my old carb, except my old carb doesnt have the choke, the butterfly, or the vacuum thing on the back of it(not sure what its called) or any of the linkage, thats why i bought the other carb so i could have the same carb with all the pieces that i was missing on my old one

my new carb is all clogged, so i had to put my old one back on just so it will run, so i can get back and forth to work, until i get my next day off to rebuild it, i hooked up the old one exactly how it was, without the choke and everything, the previous owner had it set up that way, and i drove it like that for a year, and the only real problems i had was hard cold start, and the engine would bog under full throttle, now that the old one is back on its not behaving at all like it did before, its actually starting easily, so i guess thats fixed, lol, not really...
Old 04-04-2010, 06:34 PM
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Re: high idle quadrajet

well i spent all day taking apart and cleaning the new carb, i put it on, and started the car right up, the car has never run so smooth, im proud, lol
Old 04-05-2010, 06:21 AM
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Re: high idle quadrajet

Good job! Not so scary once you do it a couple times.
Old 04-06-2010, 01:07 PM
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Re: high idle quadrajet

thanks, yeah it definitely runs smoother.. once its finally running, but i have another weird problem, ive been off for a couple days, and when i went out to start it this morning, i sat there and cranked it for i dont know how long, with no dice, so i got out of the car, threw the hood up and expected to see gas everywhere, like it did when i put it on before, but there was no gas, but there was pressure in the line, so i know fuel was getting to it, so i got in the car and tried to start it again, and it sputtered a couple times, and then it finally started, and it ran really rough until it warmed up, just like my old carb, except it runs smoother than the old carb when warmed up

my only thought is fuel isnt getting through the carb very well, but when i cleaned it, the cleaner got through all the jets and passages just fine

the engine doesnt bog any under full throttle, so i dont think its another clog either

any thoughts? thanks a lot for the help

Last edited by wwwyzzerdd; 04-06-2010 at 01:31 PM.
Old 04-06-2010, 02:10 PM
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Are you tapping the throttle before you go to start it?
Old 04-06-2010, 02:14 PM
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Re: high idle quadrajet

i didnt at first, but after trying to start it with no dice, i tapped it
Old 04-06-2010, 03:32 PM
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When cold, you need to give it about a half throttle stab and let it off again before you turn it over. This sets the choke to closed and puts the throttle on the high idle cam. After it starts, just tap it after its been running for a few seconds and the idle should drop down one step. As the engine warms up and you drive it for a few minutes, the choke should fully open and the idle drop down to "normal".
Old 04-07-2010, 01:22 PM
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Re: high idle quadrajet

still just as hard to start this morning, the choke doesnt even work, so the butterfly flap stays all the way open all the time, the coil inside the choke is good but the 12v terminal on the side is corroded all the way through, i broke it off trying to adjust the wire to it, which im fairly mad about, cause thats pretty much the only reason i bought it

with my old carb, all i had to do to start it was crank it and hit the gas a few times and it would fire right up, and i would stay on the gas until it was warmed up enough to idle on its own

with this one, i have to keep cranking and cranking and cranking and it will start to sputter, then ill keep cranking some more, and then it will sputter again, then a little more cranking and it will backfire and finally sputter up and start, then i still have to stay on the gas until its warmed up enough to idle on its own, im afraid im going to burn the car down doing this, i really want to get this carb in good shape

i really dont mean to sound like a whiny person, or a broken record, i really just dont even know where to start troubleshooting this, i would just take it to a shop, but i dont trust anyone at a shop around here, ive already been screwed over by a couple of them, i got charged 45 bucks for them to put in a thermostat! and i still had to buy the parts! i figured like 20 bucks, but no

*edit* i was wondering, is the choke supposed to be closed when not running and cold? because i noticed yesterday(before i broke the terminal off of the choke) after the car was warmed up, i killed the engine and i noticed the butterfly had a lot more tension on it than before, like the choke was trying to open it more than it could go, and that makes me think when i put the coil back in, i didnt position it right, that would explain why the choke is always open

Last edited by wwwyzzerdd; 04-07-2010 at 02:09 PM.
Old 04-07-2010, 02:08 PM
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A carb'd car that runs properly when fully warmed up will require a choke to start and run when cold. Even when it is "hot" outside.

It is possible to install the choke thermostat and not get the coil properly attached to the lever inside the housing. But, if you broke off the electrical terminal, you need to address that first.
Old 04-07-2010, 02:31 PM
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Re: high idle quadrajet

yeah for sure, im about to go take that choke off and see if i can manage to solder the thing back on

im just worried about why it takes so much longer for the car to start with this carb, than it did with my old one, same carb, both with the butterfly completely open and without a choke

im hoping its just because the choke, but i still dont understand why my old one would start it much much easier, i guess it could possibly be that it may be leaking fuel through the bowl plugs on the bottom, guess ill have to take it off and see

again, thanks for the help

Last edited by wwwyzzerdd; 04-07-2010 at 02:38 PM.
Old 04-09-2010, 08:31 AM
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Re: high idle quadrajet

It takes longer because your old carb was flooding out and running rich! Now you've got one that works properly (except for the choke) and it'll be a bear to start from overnight-cold without the choke working. Pumping the gas several times to shoot some in via the accelerator pump helps.

You can buy a new choke element from your local auto parts store- they're about $35 in my area. Yes, they can wear out over time (the little electrical heater inside burns out and won't heat the choke very well, or at all sometimes). A quick test of the choke's resistance with your Ohm meter will often give a good indication of it's condition (measured between the electrical terminal and the metal backing plate, or carb body if it's already installed). AT ROOM TEMPERATURE a brand new one will be around 5-10 Ohms. A used but still good one can be as high as 20 Ohms. Anything over 25 and it's replacement time.
Old 04-10-2010, 06:28 PM
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Re: high idle quadrajet

well this choke is no good, so ill post back when i get a new one, to see if it fixes the problem, im gonna try to go monday afternoon to get another one

thanks for the info
Old 07-04-2010, 07:08 PM
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Re: high idle quadrajet

i got a new choke a few weeks ago and got it working great for a while, but its acting up again... i just want tpi... anyways, i was driving back from a friends and i had a really low idle the whole time, on the edge of stalling at 190, the butterfly was open like its supposed to be, so its not the choke

and today i went out to mess with it and i was messing with the idle screw and the uh.. the other screw under the choke, cant remember what its called, and i got it to idle right again, so i was like cool, i hit the gas just to test it, got it up to 4000 rpm and let off the gas, as soon as i let off the throttle the idle dropped down to almost dying again, at this point im extremely aggravated with it, so i figured i would ask here, maybe someone can throw me an idea, thanks
Old 10-20-2010, 12:27 PM
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Re: high idle quadrajet

Originally Posted by Damon
It takes longer because your old carb was flooding out and running rich! Now you've got one that works properly (except for the choke) and it'll be a bear to start from overnight-cold without the choke working. Pumping the gas several times to shoot some in via the accelerator pump helps.

You can buy a new choke element from your local auto parts store- they're about $35 in my area. Yes, they can wear out over time (the little electrical heater inside burns out and won't heat the choke very well, or at all sometimes). A quick test of the choke's resistance with your Ohm meter will often give a good indication of it's condition (measured between the electrical terminal and the metal backing plate, or carb body if it's already installed). AT ROOM TEMPERATURE a brand new one will be around 5-10 Ohms. A used but still good one can be as high as 20 Ohms. Anything over 25 and it's replacement time.
5-10 ohms - that's what I wanted to know. I love the search feature.
I'm working on a friends car and it's got a horrible bog under even the lightest throttle when it's cold. After 15 minutes of warming up, it runs fine, but until then, I can barely make it through sets of lights. Checking the voltage on the thermostat while running (and wire connected) shows ~14V, so i'm hoping the thermostat just isn't properly grounding to the carb -- cheaper than a new $60 thermostat here...
Old 10-20-2010, 01:02 PM
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Re: high idle quadrajet

Are all the other cold-starting features still in place? Exhaust crossover, EFE, thermac...?
Old 10-20-2010, 01:12 PM
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Re: high idle quadrajet

No, the PO made those long gone. EX crossover - I'm not familiar with this, but I think it's gone.
Thermac (bottom of air cleaner) is not hooked up to anything.
EFE i'm not familiar with.

My TA ran pretty smoothly from cold to warm without those things, but this car is horrible for that. When the choke is set up right (thermostat such that it snaps shut, idle speed is right, choke pulloff cracks the choke blade open ~3/16") it'll cold start perfectly. It'll run great for about 1 minute (the time where it would normally be opening more), then it won't accelerate. Massive bog.
Then after 10 minutes of driving or so, it's warm, and it runs well. It's the transition time that's killing me.

When the car is started, the choke thermostat - should that show 14V? When hooked up and working i'd think since it's grounded it'd show less... But I don't get a choke light on the dash (which I would get if I pulled the wire off the choke while running--right?)
Old 10-20-2010, 01:45 PM
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Re: high idle quadrajet

Pulling the choke wire off while it's running won't do anything, it'll just make the light stay off when the engine is off.

There should be full voltage across the choke while it's running.

M4ME or M4MED?
Old 10-20-2010, 01:49 PM
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Re: high idle quadrajet

M4ME as far as I know. Never heard of the D variant?
ok, full voltage across the choke while it's running = good. I'll check the resistance of the choke (and any spares I have at home) when I get back.

In reading another thread, someone mentioned transition warmup bog due to a timing issue. Ie ignition timing. I recall using manifold vacuum ( I think..), and bumping up the timing slightly. I'll have to re-check the base timing when I get home as well.
Old 10-20-2010, 02:06 PM
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Re: high idle quadrajet

M4MED has the double-capacity accelerator pump to increase the pump shot when the engine is cold.

IIRC, factory timing was through a TVS to delay application of vacuum advance until the engine was warmed up.

Remember that the factory choke setting is for when everything is in place and functioning. When you've taken away some of the features that help warm the engine up quickly, don't be surprised if you have to have the choke on longer.
Old 10-20-2010, 02:10 PM
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Re: high idle quadrajet

oh ok, no it doesn't have the double capacity pump.
Oh, interesting information re: TVS.

Yes, I noticed that with my TA - I had the choke CRANKED over to be on for a good long time. Then again, that engine got quite warm quite fast.

I'll make sure the choke thermostat is good, then tweak it to be on a bit longer first.
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