On 01 Oct 2004 18:39:03 GMT,
(Playintennis5274) wrote:

and FIY, what do you think happens whun a plunger pump forces liquid out ? ?
We call that a vaccuum which the draws more liquid.

Vacuum does not draw liquid. Atmospheric pressure does. With a
gravity feed system on the bed of a truck you can at best expect
he equivalent of 15 psi of push. 15 psi may not be enough to create
the minimum flow rate desired.