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sudden rich condition

Discussion in 'The Hokey Ass Message Board' started by ykp53, Dec 15, 2011.

  1. ykp53
    Joined: Jun 26, 2006
    Posts: 429

    from macon ga

    I keep a log of everything that I do to the car, and I have noticed that the intown gas mileage has dropped from a constant 14 mph to 8 mph for the last two tanks. I have also noticed that the exhaust seems to smell rich after i turn it off. I did a quick check under the hood tonight a see nothing wrong. PVC is connected , choke appears to be functioning. This is a 300/327 with a year old edelbrock 600 cfm carb. The power level seems fine. No hard start or run on issues. No back fires. Nothing has been modified to the car other than a oil change in 6 months. What could case this condition. Where should I start checking?
  2. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    from BC

    Vacuum piston not working right? Pull the air cleaner off, and make sure its all the way down at idle. Might have got some shit in there, causing it to stick in the up position.
  3. Buckster
    Joined: May 3, 2010
    Posts: 228


    Check the color of your tailpipes-should be a grey color. If black, then the carb is running rich. These conditions are only if you are getting out on the highway for 10 miles or so.
    Around town the accelerator pump & stop & go traffic will keep it too rich to diagnose by looking at the tailpipes.
  4. KoolKat-57
    Joined: Feb 22, 2010
    Posts: 2,928

    from Dublin, OH

    Could it be a winter blend gas that they are selling in your area?
    My mileage drops in the winter!
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  5. r8odecay
    Joined: Nov 8, 2006
    Posts: 787


    Float sprung a leak, ... or crap in the needle seat, bowl overfull... my worthless 2 cents.
  6. spooler41
    Joined: Feb 25, 2007
    Posts: 1,099


    What a let down ,after reading your title, I thought you may have found a big bag of cash. Good luck with your fuel problem.

  7. Too much fuel or too little air. I would check the air side first..air cleaner clean and unobstructed?
  8. Don't get me started ..... but, when you said "Edelbrock carb" .... well .... let's just say "I am not a fan" of those.
  9. mustang6147
    Joined: Feb 26, 2010
    Posts: 1,847

    from Kent, Ohio

    ^ what he said x2
  10. Heo2
    Joined: Aug 9, 2011
    Posts: 661


    leaky floatvalve to high fuelpresure or
    debris in the valve
  11. caseyscustoms
    Joined: May 15, 2005
    Posts: 1,031

    from st.joe, MO

    Change your fuel filter...
  12. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,476


    Choke not opening right or all the way.
    Dirt under needle or needle sticking.
    Vacuum piston not working as previously mentioned.
    Timing off for some reason. You might want to check the vacuum advance to make sure it is working right as that would cause the timing advance to be less than desired.
  13. I thought this was about a money you hit it rich!!!...oh well..:eek:
  14. junk yard kid
    Joined: Nov 11, 2007
    Posts: 2,718

    junk yard kid

    Could be a dirty air cleaner.
  15. ykp53
    Joined: Jun 26, 2006
    Posts: 429

    from macon ga

    Well I did some investigating. I guess I had a small pin hole in the line from the carb to the distributor.I measured a vacuum of 21 at the carb but just for grins I measured the other end of the line and it only read 7. So im guessing I developed a small vacuum leak that was causing me to run rich. Thanks for the tips and I will update to let everyone know if that was it.
  16. Iceberg460
    Joined: Jun 6, 2007
    Posts: 880


    Good to hear ykp.

    I've seen this too, they run a higher ethanol content in the winter. May be contributing to your problem. Ever notice how gas drops way down in price when it starts to get cold?
  17. zman
    Joined: Apr 2, 2001
    Posts: 16,558

    from Garner, NC

    are you running a fuel pressure regulator?
  18. You are probably riding around with your left foot on the brake, remove your foot and you will be right back to 14 mph just like before.
  19. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    from BC

    Never even noticed that! You a funny guy...:D

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