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choke light

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KENNY, Dec 8, 2000.

  1. KENNY

    KENNY 1/2 ton status

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    I HAVE A 84 SIVERADO K5 WITH MANUAL 4SPD,305. THE FIRST COLD DAY OF THE SEASON AND THE CHOKE LIGHT COMES ON AND THE ENGINE REVS HIGH FOR WHAT I THINK IS TOO LONG A TIME. I'M NO MECHANIC BUT THIS SEEMED LIKE A LONG TIME TO ME. ONCE THE ENGINE WARMED THE LIGHT WENT OFF AND THE ENGINE REV CAME DOWN. SHOULD THIS LIGHT COME ON. IS THIS NORMAL FOR THIS CAR?
     
  2. Blue85

    Blue85 Troll Premium Member

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    You know, I have wondered too, just exactly what that choke light indicates. On my 85, the choke light comes on before the engine is started on cold days. After the oil pressure comes up, the light turns off. The engine runs at about 1000rpm and slowly increases to maybe 1200rpm as the choke opens up and the engine warms. Then the idle speed can be reduced by tapping the throttle, which knocks the choke down a step or two on it's cam and takes it down to 700 or 800rpm where it normally idles.

    Which is right: a light that comes on and turns back off again right away, or a light that stays on as long as the choke is active?

    How high is it revving?

    Another interesting note: if the engine is ever stalling or dying for some reason (such as a plug wire melted to the manifold, just for example) the choke light comes back on! I think that it is related to oil pressure and not to the choke, since the choke can't phsically be activated without turning the engine off.

    "If it aint broke...Make it work better!"
     
  3. KENNY

    KENNY 1/2 ton status

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    the engine revs as a normal one would but my guess is that it revs high for a prolonged period of time. once warm it does revert to a normal rev. I don't have a tach on it yet but it seems ok after warming up.
     
  4. Blue85

    Blue85 Troll Premium Member

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    I'm curious: how does the light know that the choke is on? Is there a switch on the carb that closes whenever the choke is not fully open? I know that there isn't one on mine.

    "If it aint broke...Make it work better!"
     
  5. KENNY

    KENNY 1/2 ton status

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    the choke has a wire connected to it that leads to the choke light on the dash. the light goes off if you take the wire out.
     
  6. Mr Red

    Mr Red 1/2 ton status

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    I have an '86 and the choke has been problematic but I do know that it's light should not be on all of the time. It should only be on when you first turn the key (like a check of the bulb), then go off. I'd say you've maybe got a short somewhere or the choke thermostatic coil is broke. But, on the other hand, the description of the fast idle sounds right. Like the other post, mine will fast idle for about 3 minutes (5 if it's real cold out), you here it throttle down off the high idle cam and after that, you tap the throttle and it drops down to normal idle.

    A Haynes or Chilton book has some diagnostic info on your choke. Suggest looking at those. Oil pressure's not involved unless you have a computer controlled carb (ECM unit).

    Something may be sticking. Till you get your hands on a book, clean the throttle real good (while cold). Then warm it up and clean the throat of the carb real good while it's running. After it cools down, lubricate all the linkages and throttle.

    Good Luck,
    David
    '86K5
     

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