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Spark Plug turned Black???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Burt4x4, Mar 7, 2000.

  1. Burt4x4

    Burt4x4 3/4 ton status

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    I just pulled my Spark plugs out and one of them the tip was black were the rest were light brown??
    Could this bee a faild plug??
    any thoughts??
    Burt4x4

    Rock ON!
     
  2. Goose

    Goose 1/2 ton status

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    Sounds like something is not quite right. I'd check the spark plug wire for that plug and see if it isn't cracked and not firing all the time. Also, the rearmost plugs seem to foul sooner that than the others. Something to do with how the engine sits and oil leaking by the valves. I assume it's the same heat range and type of plug as the rest.
     
  3. Eric77

    Eric77 Registered Member

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    Also check to see if the gap is larger on that one plug than on the others. Is it worn more than the others? That would cause poor combustion because of weaker spark. Stranger things have happened!
     
  4. K5 NUTT

    K5 NUTT 1/2 ton status

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    Sooty black i hope..or oil caused black? Sooty usually indicates rich mixture but with only one hole doin that ohm test that wire and see if its in the range of say 9 Ohms...over 12 and up you have a resistance problem in that wire.

    AZBLAZER

    1979 K5
    1976 K5 Chalet
    1972 K10 Suburban
     

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