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Old 07-23-2012, 01:10 PM   #1
l79m20
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Vacuum problem

I was under the hood of my blazer and noticed that several of the vacuum lines were cooked and cracking. So I went and bought new hose and started to replace them. I did it one at a time until all were done. Now all of a sudden the thing wont idle after the choke is off. It even dies when driving. Ive looked at this thing over and over and over again and I can't figre anything out. Any help or routing diagrams would be helpful. I know there is a diagram on the core support and as far as I can tell Ive got it right. Its an 84 with 305 low alt auto
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Old 07-23-2012, 02:24 PM   #2
l79m20
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Re: Vacuum problem

This is the piece that had really bad ends that I changed out today. None of the auto parts store sell it and chevy cant order it either, but I was told I could just bypass it which I did, but somehow I didnt get a hose going in the right place.


The bottom right is the hose that I cant figure out where it goes to.
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Old 07-23-2012, 04:56 PM   #3
l79m20
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Re: Vacuum problem

i feel like i have put a line in the wrong place. I can suck on the end of the vacuum advance line and I can hear in the va that its working. When truck is running(with a little help from wife) and I unplug the vacuum advance hose the truck dies immediately. I still have no idea whats causing this. I have seen posts about a decell valve but none of the parts stores have it.
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Old 07-23-2012, 10:40 PM   #4
russgt
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Re: Vacuum problem

Out of curiosity, what is the idle RPM set at? Is it possible that over time the idle was adjusted down to compensate for the vacuum leaks that kept creeping the idle speed up?
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Old 07-23-2012, 11:16 PM   #5
l79m20
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Re: Vacuum problem

No ive checked the idle screw and it is still factory tight like it should be. Truck only has 80k miles, but sat undriven for almost 6. Im having it looked at by a mechanic friend tommorow.
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