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by Anonymous on January 23rd, 2007

Anonymous

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I have a 1978 Corvette 350 engine.When it sits for 2 to 3 days I have to pump the gas pedal about 20 times. After 3 days I have to prime the carb. I have a new fuel pump,a new rebuilt quadrajet carb & a check valve in the line to hold the gas in. Thanks!

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Answers. 12 helpful answers below.

  • by SportsCarsUnlimited on June 19th, 2008

    SportsCarsUnlimited

    Hello
    When a quadrajet carburetor is rebuilt on the main body on the bottom you will find two plugs that are crimped in place. They are under the main jets. These plugs are to seal the hole from the machining of the main jet fuel passages when the carb was new, When you soak the main body in carb cleaner for the rebuild the seals under these plug dissolve and cant be replaced. In the carb rebuild kit there is a small foam like seal that gos between the main body under these plugs and the base plate, That takes the place of the now missing seals. If this is not installed when you rebuild the carb, when your car sits for a day or two the fuel in the fuel bowl will leak past these missing seals in to the intake manifold, Then when you go to start motor will have to crank over intell the carb is refueled (same as being out of gas) Very easy to fix. Hope this helps.
    David

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  • by OldSkiDoo on May 21st, 2007

    OldSkiDoo

    If you pull your Quadrajet off and flip it over you will see 2 lead plugs in the primary side. These plugs being lead in a aluminum environment tend to leak fuel into the intake after the carb ages causing the fuel to drain from the bowl after it sits for a while. Usually gases down the oil in the crank case in no time. I use a 2 part epoxy thats impervious to gas. Clean the area well before you apply it. I have not had one releak yet. I do that on all Quadrajets I rebuild.

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  • by Dog_Star on January 23rd, 2007

    Dog_Star

    This may sound simplistic, but from your engine symptoms you had better check the level of the float valves in the carby, it sounds like the float level is to low, this is a common occurrence with a rebuilt carby.

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  • by joe on June 4th, 2008

    joe

    Just because the carb is new does not mean it is working properly. It sounds like the gas is getting out of the carb either by a leak or evaporation. What type of breather do you have. Is the car stored in a hot place. The use of winter blended gas in a hot enviroment can cause evaporation of the gas in the carb.

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  • by carguy1 on September 7th, 2007

    carguy1

    i would say carb is leaking fuel back into motor as opposed to back thruogh fuel tank start and run for awhile and then shut off pull air filter housing off and check to see if carb is leaking fuel into motor

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  • by magyver on March 18th, 2007

    magyver

    hi this means your carb float level is set too low ,if this is low there wont be enough gas in there for your cold start

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  • by freebee on February 15th, 2007

    freebee

    I had same problem. i had minute fuel line leak on top of tank. It seems like the vacuum in vent cannister was draining the float bowl back thru. vent line. worth looking into.

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  • by toe-tag on January 23rd, 2007

    toe-tag

    Is it a mechanical or electric fuel pump? If mechanical try an electric fuel pump.

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  • by Universe Of Life on January 23rd, 2007

    Universe Of Life

    Maybe the choke is not working, check the carb to see that the butterfly is cosed when you choke it ... If a choke does not work it sometimes takes more fuel to start a cold engine ... The chokes function is to cut the air intake down allowing more fuel to the engine.

    Or your carb could be leaking and when you go to start there is no fuel in the float chamber so you have to wait for the fuel pump to refill it again.

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  • by Junk Yard Dog on January 23rd, 2007

    Junk Yard Dog

    maybe you need a higher psi fuel pump....

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  • by samsondee on April 30th, 2012

    samsondee

    you may have heat transfer problem. after you drive and engine heats up, is it hard to start, like it is flooded? drive and get engine hot, turn engine off and remove carb breather. look down into carb, if you see smoke or gas dripping from inside back of carb, it has a heating problem. you need to add a open spacer, wood fiber laminate to reduce heat transfer to carb. 1/2 or 3/4 inch from wood should work. you can make one or purchase from Edelbrock

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  • by tech4diesel on September 12th, 2008

    tech4diesel

    electric fuel pump will fill carb if u wait 5sec or u can take carb off and reseal plugs in bottom plate

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You're reading I have a 1978 Corvette 350 engine.When it sits for 2 to 3 days I have to pump the gas pedal about 20 times. After 3 days I have to prime the carb. I have a new fuel pump,a new rebuilt quadrajet carb & a check valve in the line to hold the gas in. Thanks!

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