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89 k5 runs rich?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 468ratman, Dec 24, 2002.

  1. 468ratman

    468ratman Registered Member

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    I just bought a 1989 k5 w/ 350 tbi 700r4

    The problem is when I start the truck it runs great, then as it warms up into it's operating range it starts to stutter and chug like it's choking on gas. (I can smell the gas)

    It does this until the stat opens an then it smooths out and works good.

    Is this a computer problem? My temp gauge was acting funny so I took a look at it and found that the wire was green all the way through. So I cut that part out and now the gauge works but the chugging persists.

    Any leads you can give me are appreciated.

    thanks.
     
  2. TopOff

    TopOff 1/2 ton status

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    Did you "ask" the computer if there are any codes?

    That's where I would start.

    Do all the usual stuff, check the air cleaner - I am not sure on the 89's there maybe a thermo-vacuum switch which should open the heat riser so the intake takes in heated air when the engine and intake are cold.

    Good luck.
     
  3. 468ratman

    468ratman Registered Member

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    How do I "ask" it?
     
  4. TopOff

    TopOff 1/2 ton status

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    Do you know where the ALDL connector is?

    You jump the pins A and B with a paper-clip.

    Then you will get a code flash on the check-engine light.

    Check your Haynes (Chilton or any other) manual.
     
  5. 468ratman

    468ratman Registered Member

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    Ok, i'll do that and see what I come up with....
     
  6. Thunder

    Thunder 3/4 ton status

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  7. 468ratman

    468ratman Registered Member

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    I get a "12" that is, "flash-space-flash-flash"

    That isn't on the list. Does that mean its ok?
     
  8. imiceman44

    imiceman44 1 ton status

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    That is the hand shake.
    If you didn't get anything else after that it means no codes stored.
     
  9. skelly1

    skelly1 1/2 ton status

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    Sounds like the computer is overcompensating for a cold condition. Before closed loop operation, the computer looks at very few inputs. This problem could be the coolant temp sender. It seems to me that this would be a very cheap part to throw at it. A plugged air filter will make it run overly rich too.
     
  10. 468ratman

    468ratman Registered Member

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    What about the pre-heater hose? aka heat stove or that silver tube that goes from the exhaust manifold to the air filter.

    Could that cause me trouble? Mine was missing. I picked one up at NAPA tonight and put it on just in case but what do you all think?

    Thanks.
     
  11. skelly1

    skelly1 1/2 ton status

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    It helps heat the intake air, but not enough to make it run as rich as described.
     

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