FUEL SYSTEM PROBLEM(Vapor lock?)

Discussion in 'Troubleshooting & Diagnosis' started by Stak, Apr 24, 2009.

  1. Stak

    Stak Veteran Member

    189
    0
    Dec 10, 2004
    Northern AL
    In the summer time, My z runs a lot warmer, and when I shut it off for 10 or 15 minutes, crank it and take off, by the time it shifts into 3rd, it cuts off like its starving for gas, the only thing i can figure is that maybe the gas it getting too hot from the under hood temp, it never does it in the winter time, only hot weather, and it has done it with my quadrajet, holley and my prosystems carb, it does it with the mechanical or electric fuel pump, I even have a new gas tank and 1/2 fuel line and it still freakin does it, but only in the summer time( u know how u can feel the heat even though y dont have it on?) l When it shuts off, and i try and crank it back up, i have to hold the pedal to the floor and it will finally start and bust up terribly then finally it will clear up, but it may shut off and do it all over again. Please tell me im the not only one to experience this problem> Thanks in advance as always!!
     
  2. muscl car

    muscl car Veteran Member Lifetime Gold Member


    here's what you need to do ......


    1] make sure you fuel lines are placed far enough away from area that get hot like exhaust pipes/headers and engine block surfaces . also make sure it has at least a few inches of an air gap surrounding the fuel lines so cool air can flow over them .if the fuel lines are to close you can get special heat wraps that will keep the fuel lines from excessive heat

    2]make sure your fuel pump is putting out it's max pressure if not during the warm months this will cause the fuel to percolate as it isn't moving quick enough

    3] purchase and install some sort of insulated carb spacer preferably wood and 2nd being a phenolic spacer of at least 1" tall .this will allow the heat to be removed from the carb and not allowing the fuel to boil in the bowls


    heat sleeving for the fuel lines ..

    http://www.jegs.com/i/JEGS/555/32014/10002/-1

    [​IMG]


    carb heat shield ....

    http://www.jegs.com/i/Mr.+Gasket/720/3710/10002/-1

    [​IMG]


    wood carb spacer ....

    http://www.jegs.com/i/Edelbrock/350/8720/10002/-1

    [​IMG]
     
  3. Stak

    Stak Veteran Member

    189
    0
    Dec 10, 2004
    Northern AL
    Thanks Muscl Car, I'm gonna give that a try today. I actually put that carb heat shield on yesterday and drove it around last night( thought it fixed it) but on my way home it started acting up. So today I'm gonna find that wooded spacer, and that sleeve for the fuel lines, and go over my lines all together and make sure they aren't right up against any heat, thanks for your help, I post back this evening or tomorrow after I see how it does...........
     
  4. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

    8,186
    1
    Jun 22, 2003
    Endicott, NY
    Check the fuel pump pressure. I had a similar problem with our C10 pickup. Would start and run fine as long as the truck was cold but NOT when it was warm. The pump pressure has to be between 5 to 7 psi.
     
  5. jroach

    jroach Veteran Member

    1,267
    0
    Apr 9, 2007
    petersburg MI
    maybe could use a trans cooler for fuel
     
  6. bad71camaro

    bad71camaro Member

    94
    0
    Apr 30, 2009
    greenback,tn
    i would like to get a answer to the same question ive replaced all the rubber lines on my camaro,3 fuel pumps,3 carbs, air gap intake,heat wrap,heat shields, and still if the car gets above 180 its done boils the fuel or so called vapor lock i never had this problem until i put a 406 in it i hope someone can help
     
  7. grasmo

    grasmo Veteran Member

    892
    0
    Dec 21, 2005
    tallahassee, fl
    i just went through this same thing and think i finally got it fixed. if it was any hotter than about 75* ambient, my carb would "spit" fuel out of the vent tube. i mean it would spit it like 3-4" out of the tube. i changed everything! even welded a fitting in the bottom of the tank for a new supply tap for my blue pusher pump. what was really strange is the carb. was never hot. the fuel was not hot in the bowl. i've had engines and fuel systems that were subjected to much more heat and never had a problem. i honestly believe they've changed something in the gasoline. anyway what i did was install this orifice in the second outlet port of my dead-head regulator and returned the fuel to the tank:

    http://www.mcmaster.com/#orifices/=1ok3vg

    i used the 2822t15 with a .032. i also went back to 3/8" supply line. i did have 1/2". the idea is to keep the fuel moving. so far so good.
     
    Last edited: May 1, 2009
  8. Venom73

    Venom73 Veteran Member Lifetime Gold Member

    1,415
    0
    Feb 4, 2007
    Louisville, Ky
    I have the EXACT same problem. Let us know what fixes it because your issue is so spot on with mine it will probably require much of the same fix. Thanks to Muscl car, I will buy that hose for my fuel line.
     
  9. ZHUGGER

    ZHUGGER Veteran Member

    634
    0
    Apr 30, 2003
    Guyton,Ga. USA
    so, hate to bring back an old thread, but did anyone get a fix for their carbs??
     
  10. Venom73

    Venom73 Veteran Member Lifetime Gold Member

    1,415
    0
    Feb 4, 2007
    Louisville, Ky
    Mine isn't fixed yet:(
     

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