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post #1 of (permalink) Old 09-14-2003, 02:17 PM
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High Idle chevy

My dad asked me this week if i could get the old 87 1 ton chevy dump body running again, It's got a TBI 350. A little charge of the battery she fired right up. After it had warmed up the idle was pretty high (don't have a tach to get actual rpm). I think it's a vaccume leak somewhere. The manifolds smoke pretty bad, they are cracked and need to be replaced, I don't think this would have any affect on the idle but i'm not 100% sure. Like i said, it's been sitting for a while so.. any ideas? Thanks.
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post #2 of (permalink) Old 09-14-2003, 02:18 PM
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Re: High Idle chevy

sorry about the repost, my computer was acting funny and i wasnt sure if it went through
post #3 of (permalink) Old 09-14-2003, 02:40 PM
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Re: High Idle chevy

What year was this? '87 was it? I'm not sure on the TBIs but on a carburated one to start it you quickly push the accelerator down all the way and release it before you crank it. That sets the choke. Then after it's warm do the same again to get it off high idle. It sounds like your choke is still set. When I say push it down quickly I mean that, don't try to wind it up, you're just trying to unset the choke. It should come off high idle shortly above 100 degrees on the Water Temp guage, assuming your gauge works.
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post #4 of (permalink) Old 09-14-2003, 10:00 PM
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Re: High Idle chevy

It's TBI..forgot to mention, if i shift it into gear the idle kicks down to perfect and then when i take it out of gear the idle shoots right back up.
post #5 of (permalink) Old 09-15-2003, 02:05 AM
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Re: High Idle chevy

Yes actually in one of your posts you said 350 TBI. Anyway...did you actually try mashing it down and releasing it to get the choke off? Sounds about right, you put a load on it by putting it in gear, the idle fell...if you take your foot off the brake it'll probably do about 25mph (at least our 454 does on high idle). Try unsetting the choke like I mentioned.
post #6 of (permalink) Old 09-15-2003, 07:24 AM
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Re: High Idle chevy

yeah, i tied mashin the throttle and tapping it a few times but the idle would not kick down
post #7 of (permalink) Old 09-15-2003, 06:04 PM
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Re: High Idle chevy

Okay, hmmm. I'm not sure on the TBIs, but I know on the carbed ones it needs to be warm to come off high idle, AND (I just remembered) you should have the heat riser hooked up. It'll be a 1"-1.5" tube going from the pass. side exhaust manifold up to the bottom of the air cleaner pan at some point. I know that if that isn't connected on a carbed vehicle it's gonna screw with the choke.

Anybody else have a clue here? I was real little when we had our TBI equipped trucks ('92 & '94) and grew up driving either a Vortec or quadrajet from when I had my licence.
post #8 of (permalink) Old 09-15-2003, 08:12 PM
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Re: High Idle chevy

It's real wierd too..i started the truck up again today, idles nice and smoth and then you can hear the idle pick-up when the engine starts to warm up, is there a sensor that controls the idle? TPS out of wack?, some kinda temp sensor? I'm stumped... cause it idles down when i put it in gear..
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