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Technical 1950 Flathead fuel problems

Discussion in 'Traditional Hot Rods' started by isellhd2u, May 3, 2018.

  1. isellhd2u
    Joined: Feb 24, 2012
    Posts: 4


    Greetings to all of the hot rod gurus out there!
    Once again I am in need of some assistance.
    I have a 1950 Merc with the stock Flathead V8 in it, the stock fuel pump, the stock air cleaner, and the stock side draft (I think you call it) carburetor. If I start and run the car every day it starts right up, however if it sits for two or more days I need to use starting fluid to get it back running. Now I'm no genius but I shouldnt have to do that. I took the gas tank out and cleaned it, the fuel pump screen is new and clean, gas is good, I ran carb cleaner through it and still have to do this if it sits for to many days. On a side note when it's been running and going down the road it will occasionally run rough like cutting in and out and when I go to gas it up there is quite a bit of pressure released when I take off the gas cap.
    Any type of help would be appreciated!
  2. Is there fuel squirting into the carb via the accelerator pump before you try cranking it over? If it's only sitting for a day or two, my guess is your floats might be too low, and what little gas is in the bowl evaporates. That may also explain the car cutting out.

    If you've got pressure releasing, your fuel tank isn't venting. Gas will expand and contract under different conditions, when it expands, you'll get a little poof of air coming out when you go to fill your tank. This is pretty normal in summer time. Try leaving your gas cap on just one click instead of closing it all the way and see if there's a difference in driveability.
  3. Try also real gasoline without ethanol to see if it makes a difference.
  4. 302GMC
    Joined: Dec 15, 2005
    Posts: 6,814

    from Idaho

    Look at the side of your fuel pump. If you can see white on the edges of the diaphragm, it's likely sucking air as soon as it sits a while. A fresh ''modern'' pump with ethanol proof parts will help. If you still have the flex hose between the pump and the steel line, they always leak air ...

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