fast idle all of a sudden?

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Swims350

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as some of you know I've had my truck apart for awhile, painting underhood and rebuilding the front end. Well I had it running before I painted underhood, ran same as before, not high on idle speed and it's pretty low on fuel, almost completely empty.

Well had it running last night and the night before, ran alright, kinda rough, maybe bad gas from being low and old, hadn't run in a month or so. It started running a little rough in the last few months anyways, and by that I mean you had to let it warm up for a long time or else it'd buck and chug, crap like that, like it was out of time, but once warmed or crammed the gas down it'd run fine.

Well I left the dome light on, killed the battery, slow charged it all day today, 2 amp charge and my charger sucks. I got home fired it up, ran GREAT!!!!!!!! well minus the high idle. I left off and let it idle, thing seemed to idle over 1,000rpm like maybe 1500 or so, only a guess, no tach.

Nothing had changed from the other night it running rough to now, except for the dead battery.

I do not think it had a code, no time to get one, battery had been out and unhooked for a month or so, at least a few weeks, then installed, ran, and this was when it was rough. This was the night before last and as I said it ran and was alright maybe a tad rough.

today battery dead, charged, now runs great just high idle. Nothing else touched. No time for a code to be thrown I think. I didn't drive it, just let it sit and idle, and revved it up.

All I know is it's running good, but way to high on the idle, used to if it ever idled high(which is hardly ever had any faster idle) then it'd stop after I revved it up. I even checked to be sure the throttle was all the way shut.
 

ChrisAU

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Check all vacuum lines and TB gasket for leaks! Easily most common cause of high idle. Does it continue to idle high after it is warm? Cold start up should be 1200-1500 RPM for a few minutes.
 

hefftone

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I know on mine the vacuum lines were very brittle. The skinny hard plastic ones anyway, they suck.
 

97__Z71

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The battery may be too low. When I had my 350 tbi, it would idle at around 1000-1500 rpm's with a low battery. My guess would be a bad battery.
 

Swims350

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battery is good, but it is LOW, and that was my guess, it being low trying to charge.

my vac. hoses are all brand new rubber ones I scrapped them junk plastic ones a long time ago. tb base gasket is new as well, may check the torque on the bolts though.

Yes it was cold and it was a few minutes, even revved it up never changed it. Once I get more fuel I guess I can better figure it out.
 
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