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eyes a burnin!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Khi5in, Jun 18, 2002.

  1. Khi5in

    Khi5in Registered Member

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    MY 86 305 quadrabog runs the sack but the exhaust stinks bad. Any where near this truck when running and you'll literally start tearing from the exhaust. no smoke no skip nothing runs great. any ideas?
     
  2. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    Where is your exhaust routed? I know if you open the back window you will get some in the cab. I just roll down all the windows and I never notice it.
    Maybe fill out your profile a bit too may help!!
     
  3. Khi5in

    Khi5in Registered Member

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    I was kinda lookin for a fix. I can't notice it while driving but stop a a gas station and they start crying and make me shut it down LOL. thanks.
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    You got one of those mix control carbs I bet. Either the solonoid in the carb died or the temp sensor on the intake that controls it died.
    If it were my truck I would get a non mix control carb off a 79-81. It will hook up just fine. The 79 will be before electric choke but you can swap the electric choke onto it no problem.
     
  5. Blue85

    Blue85 Troll Premium Member

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    I am having the same problem. Doesn't sound like it's quite as bad as yours, but my wife doesn't want to follow behind me in her car. The real fix is fuel injection. I just don't know when I'm gonna score my deal on a TPI setup. Anybody got an extra one?

    I may try to test the coolant temp sensor and solenoid sometime, though.
     
  6. Khi5in

    Khi5in Registered Member

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    I might try the temp sensor thing. sounds like a good posability. thanks
     
  7. Khi5in

    Khi5in Registered Member

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    tpi- a little futher than id like to go. Was gonna buy a tpi truck but the moey was right and it runs too good to go that far.
     
  8. Blue85

    Blue85 Troll Premium Member

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    Do you have a good description of how that mixture control works? When I rebuilt my carb I wasn't sure of it's exact role and how it is influenced by the temp sensor. Doug Roe's book doesn't have much detail on this particular Q-jet rendition (performance only matters for cars, right?)
     
  9. NITRO

    NITRO 1/2 ton status

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    Cat converter????

    NITRO
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well one wire with the truck is runing that solonoide will get 12v all the time. As the sensor on the intake warms it will very the resistance to ground causing it to change the speed that it ossilates at.
    Have you had the sensor out? Those have a taper pipe fitting thread and no Teflon tape or thread sealent should be used. It could cause them not to get a good ground to the intake. Now those carb still have idle screws. I have not personnaly set one of those up spo I don't know if you have to do anything different. I imagine you run the screws a little rich and it fine tunes them but I would check before you did that. If it's running that rich that peopl in cars behind you are complaining something needs to be done. It's going to ruin the Cat if it's left that way.
    The Solonide can probably be tested by checking the resistance on it. not sure of what is concidered a good value. This is probably where you might want to hit your local library and check out the HELM service manuals that most of the big library's have on Microfisch. Should be able to get the proper diagnostics and set up procedures for the bargin price of 10cents a copy. Bring the change cause it anoys the librarians when you ask them to break a $10 LOL.
     
  11. Blue85

    Blue85 Troll Premium Member

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    Ok, I assumed that the sensor is just a thermistor, but how does this solenoid even oscillate? If the circuit is just a solenoid and a resistor, that will not oscillate, it will just vary the amount of opening or pressure that the solenoid provides. I know that the Electronic carbs have a solenoid that oscillates a solenoid connected to the main rods, but this is not the same setup. I always assumed by looking at it that it simply "opened" or "blocked" some passageway depending on whether the engine was warm enough.

    I have pulled the connector off the solenoid before and noticed no difference in anything, although I have never done it with a cold engine in the winter.

    It really isn't terribly rich, as the plugs look good and there is never much carbon in the tailpipes.
     
  12. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well I might be wrong on it oscilating. It's been a while since I have read though my performace book. I thought it said that it oscilates to keep an average amount of regulation on the fuel mixture circuit. The slower it oscilated the more time the fuel had to pass though the circuit and as the temp rises it speeds up creating a lower flow. I'll try to reread the description if I have a few minutes tonight. Reagardless my description of how to test it was correct. Just don't know the values that the parts should read when testing them.
    I personnaly have never messed with this carb just read up on it. As for it not sooting up the tail pipe...No the soot is collecting in the cat /forums/images/icons/crazy.gif With it running rich the cat will not heat up enough to burn it off and once it packs up when it does heat up it will clog then over heat and melt then produce even more exhaust restriction.
    Now the difference between the CCC carb and this carb is the solonid is controled by a computer. The computer figures it's adjustment by compairing the Fuel ratio it reads off the O2 sensor and then uses the throttle posisiton sensor to know when your trying to accelerate. It also factors in the water temp as to when to start using the O2 sensor.
    The other carb just uses the Sensor (thermistor) to see what the temp of the engine is to lean out for better emissions.
    As far as I know the CCC was never installed on the trucks at all. Nobody has positivly identified one on a truck on this site.
     
  13. Blue85

    Blue85 Troll Premium Member

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    Actually, I always just thought that I got a slight smell because I didn't have a cat, at least until you brought up the solenoid bit. At any rate, there is no soot collecting in the cat. Plus, it would still show up on the plugs if the engine was very rich and I've been running these platinum +4's now for a couple of years and they look pretty good. The difference between the solenoids on the CCC carb and the truck carbs is that the CCC solenoid has a connection to the main metering rods ("dancing needle") and the truck carb solenoid does not. Obviously the overall system operation is a lot different, but I am just talking about the solenoids themselves from what I have seen inside my carb and pictures of the inside of a CCC carb. It is influencing mixture in some less direct way.

    It is also possible that my solenoid setup has been altered. What I forgot to mention before is that my carb had been cut to give access to the idle mixture screws when I got it. I tried one time to adjust the idle mixture, but the engine rpm never changed as I turned the screws /forums/images/icons/confused.gif . Does that have something to do with the presence of the solenoid? I adjusted the idle setting way down and still no effect from turning those screws. It idles great, though and I don't have any other problems with how it runs. And the smell really isn't terrible. Not quite as bad as a diesel.
     

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