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OK This is becoming irritating

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mudbog42

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Ok I just got my Q-jet back from jet performance for the second time now. First time I got it would run way to lean and would'nt adjust out and would get stuck in fast idle mode, sent it back, told em the symptoms and what I had on the truck and supposedly they fixed it. :laugh:

I got it back this week and just put it on today, still running lean and idling rough, and it gets stuck in fast idle.:eek1: The idle just doesn't stay stable. and I've turned the screws on it all over and can't get a good adjustment.:mad:

Should I send it back and get my money back or is there just something simple wrong with it that is causing this,:doah: also I dont see anything sticking or binding but I'm gonna check again tomorrow:confused:
 
Send it back. Go to o'reilly or your favorite part store and get a rebuilt one for under 200 bucks. My q-jet required almost no adjustment for my motor and it will run on it's side. Who needs propane or FI?
 
Vacuum leaks would explain the idle symptoms and the lean mixture, so I have to say that is where I would start too
 
Vac Leaks would also explain the idle mixture screws having no effect . On these carbs those screws only control idle . Part throttle and wot are different circuits .

And the fast idle is probably choke related . Is it hooked up to the right power source ? Is it a factory choke wire going through a oil pressure switch so it doesn't sit and cook if ignition left on engine off ? Those go sometimes , or the wiring melts etc .

Or maybe some linkage binding or choke just set wrong ?
 
Wow, you guys are giving all kinds of useful advice.... all I could do was tell him to get a new carb.:D
 
Ok got the idle down and almost smooth but alot better than before, no vacuum leaks, but the other thing that when I go into a store or something real quick and come back out and start the truck it'll start in fast idle as if its cold but the engine is still warm and I have to sit there as if its warming up again:mad: Does anyone know what is causing this?:doah: Oh yeah and is a stock harness that goes over the oil pressure sender
 
Ok got the mixture and curb idle:laugh: where they need to be but the still have a bit of a rough idle:( and the idle jumps up when you apply slight throttle. :mad:

Tested the choke-getting 12 volts, took the choke completely off, choke valve fully open, no binding, cam all the way down and again apply a little bit of throttle and it holds a high idle.:doah:

also engine completely warmed up and new o2 sensor.:D

But if you blip it it will fall back down, apply slight throttle and it holds high, why is it doing this? Is there a sensor somewhere that controls idle speed, what is causing this:( :mad1: :dunno:

ideas...anyone?
 
I sold my durn Q-jet manual and I'm not too familiar with the newer Carbs.

Can you have someone run the throttle while you watch under the hood, avoiding the fan blade of course. Maybe you'll see something you can't see from the driver seat.

It sounds like a choke fast idle or throttle stop problem but I'm just guessing. Can you tell us what year carb and a possible Rochester number? Might help to know what exact carby it is.
 
the carb # is 17085524 and i've checked while running the throttle by hand from under the hood and don't see anything unusual thats why I am so boggled and I thought it was choke related too but I took the choke off and it did the same thing
 
koldsimer said:
Send it back. Go to o'reilly or your favorite part store and get a rebuilt one for under 200 bucks. My q-jet required almost no adjustment for my motor and it will run on it's side. Who needs propane or FI?
Click to expand...

Kirven, i did just that! And have had problems ever since...Choke wont stay open(it closes with any small bump) doesnt give good amount of fuel and bogs at high rpm's....Although its not my only problem, its one of them:doah:
 
mudbog42 said:
the carb # is 17085524 and i've checked while running the throttle by hand from under the hood and don't see anything unusual thats why I am so boggled and I thought it was choke related too but I took the choke off and it did the same thing
Click to expand...

Only other thing I can think of would be a sticky power piston on your primary rod hanger. I wish Dyeager was on right about now, he's good with the Q-jet diagnosis. Might try pm'ing him.

carb #17085524 is an E4ME

Let me dig around my Chevy manual and try to find something.
 
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Okay.

According to what I'm reading some E4ME carbs had what's called a C4 system. Models with the C4 system use an ISC idle speed controller mounted on the carb and run by the ECM.

Can you tell if you've got one?
 
I'm gonna check that out in the morning but I believe I have one, oh yeah and its an E4MED--not sure if there's a difference but...
 
It's recommended you do not attempt to set curb idle speed on Computer Command Control carburetors equipped with ISC. I assume the ECM will try to counter any adjustment you make.

Anyone else on here dealt with the ISC carbs?
 
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