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TBI runs way too rich when cold...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Steve_87K5, Dec 16, 2000.

  1. Steve_87K5

    Steve_87K5 1/2 ton status

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    Location:
    central NC
    When it gets below about 35F, my stock '87 TBI runs waaaay too rich. I can smell the gas.
    Hard to start. When warm, no problem. I put in NEW: coolant temp sensor, plugs, plug wires, fuel filter,
    air filter so far. No check engine light. 250k mi on engine. Fuel press reg was
    rebuilt 2 yr ago. No other problems at all. Any ideas out there?? Thanks

    SteveB
     
  2. coopertwpk

    coopertwpk 1/2 ton status

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    O2 senser
    also check your throttle position sensor
     
  3. extremeblazer

    extremeblazer 1/2 ton status

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    i don't think that the o2 sensor has anything to do with your problem because that should be a one wire o2 sensor which means that it has to get to at least 600 degrees farenheit to work which would put the computer in closed loop. it will take a few minutes for the o2 to get up to this temperature. i've seen the same problem and it ended up being that the iac was carboned up. i would take the iac out and clean it or get a new one. i would also check for a leaking injector and clean the throttle body.
     
  4. Steve_87K5

    Steve_87K5 1/2 ton status

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    I failed to mention, that for a long time I have been getting a weak stale gas smell from under
    the hood after I shut engine off. I have suspected leaking injectors, but let it go because of cost.
    Maybe this is why I have a black film all over the inside of the TB?
    If bad injectors, new or rebuilt?

    Will ordinary carb cleaner damage the IAC (assume it must be removed
    to clean properly)? OK to douse inside areas of throttle body with carb cleaner?
    Thanks for the help.

    SteveB
     
  5. Hobbes68

    Hobbes68 Registered Member

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    Don't use regular carb cleaner on your TBI. Make sure you get cleaner that specifically states that it's ok to use on fuel injected vehicles. Regular carb clear will eat through the clear coating on your TBI causing it to be very suceptible to corroding.
     
  6. 90K5

    90K5 1/2 ton status

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    If carbon built up is a problem, suck some ATF through the PCV valve or dump it down teh TBI and it should clean it out. There will be a lot of smoke...that means its doing its job[​IMG] That should also help with the black film.

    90K5
     

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