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

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

  1. grasmo

    grasmo Veteran Member

    Dec 21, 2005
    tallahassee, fl
    if alcohol was the problem in this case the car would be harder to start when cold, not hot.
  2. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    Not necessarily. Ethanol does have serious problems igniting at low temperatures and causing cold start problems, but those problems show up at very low temperatures like -20F.
    Ethanol also has a much lower boiling point than gasoline which causes vapor lock problems. Ethanol boils at 173 degrees F which is easily reachable on a hot engine that is sitting for a while. Pure gasoline's boiling point is around 425 degrees F. It can be made to boil much lower than that using additives, but good automotive gasoline won't have additives that make is useless as motor fuel.

    ZHUGGER Veteran Member

    Apr 30, 2003
    Guyton,Ga. USA
    Exactly what mine does, still havent figured it out. I'm going to find some fuel without the ethanol!!!
  4. Jrod79Z

    Jrod79Z Veteran Member

    Sep 25, 2005
    Penrose, CO, USA
    Real Gasoline where are you?

    Thanks for all the input folks! I think I heard fuel actually boiling after my Z had sat for a few minutes after driving home one day. I need to move my fuel line away from the intake too (Aluminum with Edelbrock 650) and might try insulating the fuel line up there too. Real gasoline. Who would of thought we could not get it.

  5. tacotoy

    tacotoy Member

    Aug 27, 2009
    Denver, CO
    ive seen this happen alot with mechanical pumps, the heat soaks thru the pump after it sits for a while and boils the fuel since its not sitting under pressure.

    people have fixed it more often than not with the addition of a small electric fuel pump in line back towards the tank. alot harder for the unpressurized fuel to vapor lock if the line is pressurized thru the whole engine compartment.
  6. MrAzzhat2U

    MrAzzhat2U Veteran Member Lifetime Gold Member

    Jan 31, 2000
    Lewes DE
    Many things can and will contribute to this problem!If your car has headers and it's a heat soak problem,try this,when you park the car,open the hood to let the heat out.If it solves or reduces the problem there isn't a lot you can do short of installing an after blow fan setup to cool it off.

    As others have said,todays fuel contains a lot more ethenol than years ago and it will boil at a lower temp,a cool can will fix it.Also,someone mentioned lowering the float level,that can help,but might cause a WOT problem,this could be a trial and error method.

    I have seen a lot of this lately and think it's more of the fuel quality than anything else!This is just my opinion!

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