At 11:35 PM 10/14/99 , you wrote:
>I've consistently noticed that when I fill my gas tank after it is
>nearly empty, I feel a significant increase in throttle response. So
>much so, that I notice it without even looking for it. It stands to
>reason that the cause for this is that the added pressure exerted from
>the column of gas above it gives the in-tank fuel pump in our daks a
>nice boost.
Alternative explanation: Since the fuel pump is cooled not only by gas
going thru it but also by being submerged in gas, as you run the tank below
the 1/4 full mark the pump begins to heat up and pump less efficiently. You
surely would not notice the gradual decrease in power. Upon filling up, the
pump is once again properly cooled and working at peak efficiency giving
you the increase in power you notice. My totally unscientific reasoning
tells me that for a column of gas to add pressure to what the pump is
already pumping (if the design of the fuel pump even makes that possible),
it first has to exert a pressure equal to the pump. In other words, if the
pump is pumping at 10 pounds of pressure, a column of gas exerting 5 pounds
of pressure would not bring the pressure up to 15 pounds. The column of gas
would have to exert 15 pounds before it would add 5 pounds to the pump.
Since gas tanks are not very tall, and since gravity exerts pressure from
top to bottom and not side to side, I wouldn't think there would be much
pressure on the pump from a full tank of gas. Of course, I also think
diseases are caused by ghosts :-)
Mike Crumley 97 V6 Auto
mail to: mcrumley@airmail.net
"If we don't succeed, we run the risk of failure."
--J. Danforth Quayle
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