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Sticky High Idle

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Can Can, Apr 29, 2003.

  1. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Last week I got the 84 running smooth by finding and fixiing a vacuum leak(thanks to all those who helped but missed my update). I sprayed half a can of carb cleaner into the carb at the same time and the ol' 84 was running like a top.

    Yesterday, I fired her up and the motor slowly got to high idle(I'm still having some wierd issues with my truck reaching high idle first thing in the morning). After a couple of minutes I went out to kick her down and no matter what I did, it wouldn't kick down????

    I finally put her in D and after a couple of minutes of driving it had dropped to low idle.

    I don't know enough about the high idle side of the carb. Can anybody tell me if the high idle cam is disengaged mechanically or through vacuum? What would cause this sticky high idle?

    Friggin' carbs...... /forums/images/graemlins/tongue.gif
     
  2. Goober

    Goober 1/2 ton status

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    What kind of choke do you have?


    [rant]
    If you filled out your profile properly, it would make it easier for us to help you. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
    [/rant]


    The choke and high idle are both controlled by a lever on the passenger side of the carb. If you can find your high idle adjusting screw, it rests on that lever.

    That lever pivots on a brass bushing and if you just sprayed a bunch of crap off the top of your carb, I would bet that there is just some junk in there binding it up.

    Take your carb cleaner and spray off all the linkages on the passenger side. After the carb cleaner evaporates lube it all with WD40.



    /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
     
  3. georgiared84

    georgiared84 1/2 ton status

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    On an 84 the choke is released by electricity. There is a coil that heats up on the passenger side of your carb in the round housing. It has a green wire going to it from the oil pressure switch down near your oil filter. As the coil warms up it spreads out and opens the choke and releases the high idle. Is it missing and running rough on it's way to high idle? that could be the choke sticking closed. If it is staying at high idle for too long then that could also be the choke staying shut.
    Could be a couple of things.
    Take off your air cleaner one morning and try watching the choke when you press the gas before you start it. It should go shut. Start the engine and watch the choke. It should start to slowly open up as the engine warms up. If it doesn't it's either adjusted wrong, not receiving 12 volts, or the coil inside the thermostat on the carb is bad. Try loosening the three screws on the face of the choke thermostat and turning it clockwise or counterclockwise a little bit. That's how you adjust it.
    With the engine running try testing the current the coil is getting through the green wire with a tester. If it's getting good current and the choke still isn't moving you need a new coil. (Or go to a manual choke)
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Whoops!!!!! /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif

    It's an electric choke........

    Here's the update- I pulled off the aircleaner and watched the carb as the truck warmed up. As soon as I started the truck the choke plate opened about 1/8th of an inch(I'm pretty sure it's supposed to do that). In high idle, the motor was kind of bogging so I pulled the choke plate open by hand and the idle improved a little bit. I let it run in high for about 2 minutes and then kicked it down and the high idle cam disengaged properly.

    I'm not sure why the high idle wasn't disengaging before.......maybe when I sprayed down the carb some crap got lodged in the high idle mechanism.
     
  5. sled_dog

    sled_dog 1 ton status

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    hey you said it goes form the oil pressure switch to the choke, well I have been having a real big problem with high idle never disengaging. It rarely does and it just happens randomly. I don't have my oil pressure switch hooked up. Lost it in the engine swap. Anyway to bypass this?
     
  6. sled_dog

    sled_dog 1 ton status

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    Maybe I could wire a 12V line and switch to it and make it liek an electric manual choke?
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Oil pressure switch is so the choke doesn't operate when the vehicle isn't running. IMO probably not a big deal, although you wouldn't want to leave the key in the "run" position for very long before stating it.

    Hook it to a 12V Ignition switched source (fuse panel accessory port is perfect for this) and you should be fine.
     
  8. georgiared84

    georgiared84 1/2 ton status

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    I've seen a dash switch put in. The only problem is you've got to remember to switch it on right before you start the truck, and turn it off when you turn it off. I've just switched to a manual choke.
     
  9. sled_dog

    sled_dog 1 ton status

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    just wired a 12v line right to the choke. Need ot throw a switch on it. Well it works I don't have the high idle issue anymore. Idling a little low now, just need to adjust my idle a bit.
     

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