<VV> Electric Fuel Pump

[David Heath]

I am with Seth and Frank on this one.  I had a recent similar experience.

I have been running a rotary electric pump since the early '90s.  Never had
a bit of trouble with it.  Love it.  However, I would like to change to an
in-tank unit to help quiet things a little more.  So I started doing the
prep work of draining the tank by just not going to the gas station.  I
figured I would eventually run out of gas, I would add one gallon (started
carrying a full one gallon can in the trunk once I hit 1/8 tank), drive home
and purge the tank of the last remaining fuel.  The gauge showed E for quite
some time, then at one point I took a 90 deg right turn a little hot
(sloshing the fuel hard to the left).  The car died.  I added one gallon and
still no fuel to the carbs.  I walked to the gas station for another gallon.
Still no fuel to the carbs.  I got another gallon.  Still no fuel to the
carbs (needle still showing empty).  At this point I pushed the car home
because it wasn't very far.  I disconnected the fuel line from the tank at
the "T" where it branches off to each side.  Turned on the pump and nothing.
Next I hooked up my Miti-Vac and sucked a little fuel from the line (through
the electric fuel pump), reconnected the line, and  powered up the pump.
All was good.  
I feel I just did not have enough fuel in the tank to prime the inlet line
(I believe there is a little hump in the sending unit tube and unless you
get the fuel up over the hump, it won't prime.)  I am guessing I needed
another gallon or two.  Pump located on the vertical panel right at the
outlet of the tank.  I still haven't converted to an in-tank unit, but that
would be the right "ultimate solution".  For now, I will just not let the
tank get below 1/4 tank like I have for so many years.

Dave Heath
Cypress, CA
'65 140/4 Coupe


> 
> Message: 9
> Date: Mon, 04 Oct 2010 00:43:24 -0400
> From: Frank DuVal <corvairduval at cox.net>
> Subject: Re: <VV> Electric fuel pump
> To: virtualvairs at corvair.org
> Message-ID: <4CA95B6C.4090509 at cox.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> As Seth says, there are different pump types that do things differently,
> but in general, it is better to push a liquid than pull it. In broad
> terms, you can only suck water up 32 feet. That is the limit for
> atmospheric pressure to push the water into the vacuum (or lower
> pressure) area created by the pump 32 feet above the top of the liquid.
> Confused? Think well pump on top of the ground or pump on top of a
> building. These pumps cannot suck water more than 32 feet up. Shallow
> well up to 32 feet deep, no problem. 50 foot well? A jet pump or
> submersible is the answer, not a suction pump.
> 
> In car terms, since most are less than 32 feet high, the suction of the
> fuel will work, but since the fuel is going into a lower pressure area
> (the line before the suction pump) it is much more susceptible to vapor
> lock. remember, liquids boil at a lower temperature at lower pressure,
> Boyle's law I think.
> 
> So, proper mounting is pump below the top of the fuel level (not an old
> wives's tale, but proper installation), but it can work with the pump
> higher most of the time, just no guarantees.
> 
> As far as different pump designs go, remember the well pumps you had to
> prime to get to work? Those didn't pump air worth beans! This design
> would never suck air through a dry fuel line, yet they are a fluid pump.
> 
> Frank DuVal
>