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Please help...2500 RPM idle...Can't figure it out......

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Zeus33rd, Jul 2, 2002.

  1. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Please help...2500 RPM idle...Can\'t figure it out......

    I've been wracking my brain tryin to figure this one out....Yesterday morning I went out to let the truck warm up for a few minutes like I do every morning. Idle went straight to around 2500 and has been there since. I've played with the idle screw- It's now backed out almost all the way, alittle bit more and it will fall out. The fast idle screw IS out. The choke isn't sticking...Checked the timing....8 BTDC. Would a vacumn leak cause this? I've pretty much checked everything vacumn related that I can think of.........I'm just about at the end of my rope...Between this and $hit thats been goin down at work, I'm just about to go insane.... /forums/images/icons/frown.gif /forums/images/icons/crazy.gif
     
  2. TopOff

    TopOff 1/2 ton status

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    Re: Please help...2500 RPM idle...Can\'t figure it out......

    A vacuum leak can do this...

    Check vacuum to your TH350. Check the vacuum to your Brake booster, and your PCV!

    What carb are you running? Is it the edelbrock???

    If so, these are very susceptible to contaminaates in the gas! I was using a glass filter (SUCKY!) and it let all sorts of crap into my carb. The carbs jets didn't close all the way with the crap in it!
    Good luck!
     
  3. TopOff

    TopOff 1/2 ton status

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    Re: Please help...2500 RPM idle...Can\'t figure it out......

    BTW: How did you check timing at 2500 RPM? You should be about 30 degrees at 2500 RPM! (vacuum disconnected)
     
  4. Waxer

    Waxer 1/2 ton status Author

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    Re: Please help...2500 RPM idle...Can\'t figure it out......

    I just went through this last weekend. The cause for me wsa 2 cracked vacuum lines on the carb and sticky linkage.

    First off there was a vacuum cap where the tube for the choke goes into the carb. It was cracked.

    2nd there was another cracked vacuum line that went from the front of the carb to this diaphram on the carb. It was cracked. I replaced those 2 and I started the truck back up. It still was idling high. I then took some carb spray and sprayed the crap outta the linkage and worked the linkage. It freed something cause the idle immediately dropped and is fine now. The top of my air cleaner as well as the engine was pretty dusty so I can only assume that it was dirt/grime on the linkage causing some parts of it to stick. Maybe its the same for you.

    The fix was easy as could be to just be able to spray down the linkage a bit. /forums/images/icons/smile.gif
     
  5. arq

    arq 1/2 ton status

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    Re: Please help...2500 RPM idle...Can\'t figure it out......

    choke linkage... but sounds like a vaccum leak.

    ARQ.
     
  6. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Re: Please help...2500 RPM idle...Can\'t figure it out......

    Sigh....Of course it had to be somethin stupid. It seems that 4 attemps at the mud pit at Blazer Fest blew a bunch of mud into the spring on the end of the secondary throttle shaft thingy....Mud was holdin the secondaries open....After I sat in the frickin engine compartment for about 45 minutes poking and prodding......Finally figured that out.... /forums/images/icons/crazy.gif /forums/images/icons/crazy.gif /forums/images/icons/crazy.gif /forums/images/icons/crazy.gif /forums/images/icons/crazy.gif

    TopOff- As for how I checked the timing....I really have no friggin idea what I was thinkin when I typed that...Maybe when I was holdin the timig light thats what I wished the timing would be.....In reality the damn timing mark was no where to be seen....Just been a long couple days.... /forums/images/icons/crazy.gif /forums/images/icons/crazy.gif /forums/images/icons/frown.gif /forums/images/icons/frown.gif
     
  7. 70~K5

    70~K5 1/2 ton status

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    Re: Please help...2500 RPM idle...Can\'t figure it out......

    Kid I was going to say you probaly had some mud on the linkage as the whole motor was covered with it. /forums/images/icons/tongue.gif /forums/images/icons/cool.gif
     
  8. txbluethunder

    txbluethunder 1/2 ton status

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    Re: Please help...2500 RPM idle...Can\'t figure it out......

    i've had this happen once...it was the cruise control linkage bound up at the diaphram
     

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