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Warm starting = smoke

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blue85, Aug 7, 2003.

  1. Blue85

    Blue85 Troll Premium Member

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    Wondered if anybody had experience with a Q-Jet doing this. In general, the carb works great. Starts good in the winter, good power, mileage as expected, etc. However, it does have this one problem. If the engine is started when still warm, it seems to be too rich and doesn't want to start. I assume that the choke is closing when really it shouldn't be. I have tried to floor it before starting to hit the choke unloader, but it doesn't seem to help. When it starts, black smoke comes out for a few seconds from all the extra fuel.

    If the engine is cold or is still near operating temp, it starts great. This is not a hot starter problem, as that thing always spins well. Ignition problems could cause this too, but I don't see why the ignition would be wrong only under these circumstances.

    Thanks
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Could be the bi-metal spring in the choke housing is getting weak...

    How long has it been doing this?

    Rene
     
  3. 88Silverado

    88Silverado 1/2 ton status

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    Could be a problem with the float needle valve not sealing completly. Also, when the vehicle is shut off, the fuel in the bowls gets real hot and can start to boil forcing fuel to flow into the manifold. Sometime shut it off, pull the aircleaner assy off, wait a couple minutes, then look inside the carb throat and see if you can see gas dripping inside.

    Just some thoughts
     
  4. Blue85

    Blue85 Troll Premium Member

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    It's been doing it for months, I guess. I haven't done anything since it's only under just the right conditions that it does it: probably sitting for 30-60 minutes. The vehicle does smell a little bit of gas when it's parked, but I figured that's from the gas in the fuel bowl evaporating and coming out the snorkel since I removed that charcoal thing from the air cleaner years ago.

    I will make it a point to pull it open and look for gas spilling over and also to see if the choke is closing for the warm starts. Mayb just adjusting the choke a little bit would fix it.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Mine does approximately the same thing, although it's not smoking when I start it. (at least not that I can see through the oil smoke lol) Only real "problem" it has...starts fine cold, idles fine, starts fine if you shut it off and don't let it sit more than about 15 minutes.

    If I go about halfway with the pedal, it will start a bit easier, but I usually just hold it to the floor and start it that way. I have a feeling it's the choke, but it *could* be the well plugs leaking, since I never did epoxy them. No point fixing since the carb will be gone soon.
     
  6. Blue85

    Blue85 Troll Premium Member

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    Good point. The real fix is FI. When am I gonna get around to that?
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Nah, not gonna go so far to say that EFI is the fix for everyone. Just that there isn't much point in fixing something that isn't critical if you won't be using it much longer.

    This carb (and Q-jets in general) have given me good service. 18MPG best, runs as good as I can ask the old engine, but EFI is just better for what I am doing with the truck.

    There certainly is more to go wrong with the system, but there are just as many people having problems with carbed vehicles that they can't figure out. Look at us. /forums/images/graemlins/smile.gif
     
  8. 4DiggerDan

    4DiggerDan 1/2 ton status

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    [ QUOTE ]
    but it *could* be the well plugs leaking, since I never did epoxy them.

    [/ QUOTE ]


    NO!!! You don't say???? Leaking well plugs on a Rochester???? I've NEVER seen that happen before /forums/images/graemlins/rotfl.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
     

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