<VV> Elec fuel pump

[Joel McGregor]

Being an engineer you should know that both sides are under pressure.  One side is a lower pressure and will vaporize at a lower temperature.  The other side just takes more heat to vaporize but it is also exposed to higher temperatures.  If the "suction" side had no pressure it would always vapor lock no matter how cold it was.  (given temperatures that are possible in the environment)

Joel McGregor

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From: John Kepler [jekepler at amplex.net]
Subject: RE: <VV> Elec fuel pump

How does any of that prevent vapor lock?

Vapor lock occurs on the SUCTION side of a pump only.....it simply can't
happen on the pressure-side.  It is caused when you have a
low-vapor-pressure fluid (say...gasoline!) that is heated to near its STP
(Standard Temperature and Pressure......I'm an engineer) vaporization point
(as in the hotter-than-a-Jalapeno-fart engine compartment of a
Vair!).....and THEN lower the pressure in the system via the low-pressure
created on the suction-stroke of a diaphragm pump.  Instead of having
air-pressure drive the fluid into the pump chamber.....it forms a gas
bubble.  The bubble expands and contracts following the pump cycle, and
NOTHING moves!  QED:  Vapor lock

By adding an electric fuel pump at the fuel tank (and at a point lower than
the bottom of the tank), you avoid heating the fuel to near its vaporization
point AND don't create any low-pressure in the feed line.  Now the line is
pressurized all the way to the carb float bowls.  While you can't pull a
bubble.....you sure as hell can push one! "Vapor Lock" on a pressure-side of
a pump is an oxymoron!

John
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