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Weird problem with Quadrajet carb.Help!!!

Discussion in 'Chevy Trucks' started by Hankster, May 16, 2004.

  1. Hankster

    Hankster Junior Member
    Messages: 16

    Ok...this one has got me totally stumped!! 75 truck..350 with new Edelbrock performer manifold and cam,headers,fuel pump,rebuilt carb etc.
    The carb works normal in all respects EXCEPT when coasting,especially on a downhill. You can drive it normally and not smell any fuel odors at all....BUT when you go down a hill at say..50 mph and coast(foot of the gas pedal,throttle closed)you'll get a STRONG gas odor in the cab....pull over,and remove the air filter housing,and the top of the carb around both front carb to manifold mounting bolts and the accelerator pump is soaked in gasoline!!! sometimes to the point it's running down the carbs side!!
    I took the carb,dropped the float level,put in a rebuild kit..changed gaskets...tweaked and cleaned until I could do no more...finally we figured maybe the top was just warped and there was nothing we could do to fix it...so we got ANOTHER rebuilt unit, cored in the old carb. Started and ran fine....when I punched it after getting on the two lane,downshifted to first...got rubber when it hit second...so it's working fine. That afternoon..take for a longer test..all is fine....top a long downgrade..let her coast....SMELL GAS!! Pull off....SAME PROBLEM!! Two different carbs....same problem. I'm out of ideas....WHY would two different carbs (bought a year apart) act like this???? Never seen this before....why does it leak/overflow/etc ONLY on closed throttle decellerating???? Turned around,drove back home...popped hood....gas all but gone now(evaporated).....no new gas showing..I'm at my wits end!! I need to be able to use this truck!!! Help!!!

    FSUPERDUTY Senior Member
    Messages: 312

    something to try which is cheap, maybe you have a defective fuel pump I know you just changed it but what else would cause two different carbs to be so over fueled like that.