Hard to Start When Hot.....Carb?

Discussion in 'Troubleshooting & Diagnosis' started by gordonquixote, Aug 16, 2009.

  1. gordonquixote

    gordonquixote Veteran Member Lifetime Gold Member

    Jul 18, 2006
    Tallahassee, FL
    Usually I take the car for a spin and come home and park it for the day. Recently I have been driving the car on weekends for whatever is going on.

    I've noticed that if I turn the car off after it is up to normal operating temperature (180*) and let it sit for a while.....I have to hold the gas pedal to the floor and crank the engine for about 4 seconds before it will fire up.....Then of course, when it fires the exhaust smells like gas until it burns off.

    Carb or timing?

    I have a 1000A battery, a CS130 alt, and a MSD6AL so I know I have plenty of spark. Carb is the Holley SA 770. Mechanical fuel pump.

    FWIW, sometimes I notice that when the car is cold and has sat for a few days/weeks, the fuel filter is empty but several people have said that is normal.
  2. Chevrolaine

    Chevrolaine Veteran Member Gold Member

    It won't start just pumping it 2 or 3 times?

    I'd guess carb if you have to hold it to the floor all the time. I can't recall any carburated engine I've had to hold to the floor to start unless they were severely flooded.

    Your not using one of those cheap see thru filters are you?!!:eek:
  3. RothrockGuitar

    RothrockGuitar Member

    Feb 2, 2007
    Crossville, IL
    Sounds like fuel leaking from one of bowls into the intake, but that is usually a Q-jet habit.
  4. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    Is your choke working right? It should stay wide open on a hot engine. If it doesn't, you will have hard starting and you will have to hold the pedal to the floor to clear the flooding.
  5. kenny77

    kenny77 Veteran Member Lifetime Gold Member

    Jul 31, 2001
    Ft. Lauderdale, FL
    Mine does something very similar. Let it set for less than like 10 min...restart fine. Let it set for 20-30 min does the exact thing as yours.

    Let the car sit for an hour or so..no problem restart fine.

    Have NEVER figured out why, in fact I've never spent so much time and effort on something and have not been able to fix it!
  6. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    That sounds like your choke is either closing too fast, or too slow to give you the correct mixture for a quick start.
    The choke is very easy to adjust.
  7. kenny77

    kenny77 Veteran Member Lifetime Gold Member

    Jul 31, 2001
    Ft. Lauderdale, FL
    No, no choke even hooked up. On my car choke is wired fully open all the time. It's like the engine/carb go into some kinda strange "heat soak" result is a flooded condition during that specific time in which you try to restart the car.
    Last edited: Aug 16, 2009
  8. Z28SSRS

    Z28SSRS Veteran Member

    May 2, 2009
    Nevada City, CA
    My 1978 does the exact same thing. A short stop, it starts fine. A long stop where it cools, it starts fine. An in between stop when it is hot, I usually have to hold the pedal down to get it to start, and even after starting if I am going slowly, like through a parking lot it might stall. I blame it on today's gas and heat soak like mentioned. Mine doesn't do this in cold or cooler weather, only hot.
  9. C-1 generation 2

    C-1 generation 2 Veteran Member Lifetime Gold Member

    Oct 23, 2005
    Imperial,Missouri USA
    Just like others have said,I mainly believe it's how they refomulate the gas.From your fuel pump to the carburetor it seems it's evaporated and what's in your carburetor has evaporated too.
    My Camaro does it all the time with temperatures above 90 and with the Corvette it starts ok but the idle is off about 100rpms until it runs a few minutes but I've got an air gap intake on the Corvette.
  10. fast12

    fast12 Veteran Member

    Feb 26, 2007
    It sounds like the carb leaking down into the intake.Like mentioned earlier in this thread. What kind of carb do you have?

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