Quote:
Originally Posted by Bruce Compton, Canada
I was not saying that vapor lock does or does not exist, I was simply asking for someone to logically explain how it can happen in a gravity feed system. ...
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It can happen due to surface tension combined with a narrow or convoluted pathway causing a bubble of gasoline vapor to effectively stick somewhere so as to block the gravity driven flow of liquid.
The science of it is no different than with "air lock," which is common in ordinary water plumbing. The best example I know is when a bath room sink sometimes acts as though the drain line is plugged, refusing to drain until you jiggle the stopper whereupon the trapped bubble of air burps out and flow resumes: This is a gravity fed system in which there is no blockage other than a bubble of gas--which SHOULD go up, but doesn't--preventing flow of a liquid that SHOULD go down, but doesn't.
Surface tension prevents the bubble from deforming far enough from its spherical ideal to slip through the "crack". Removing the stopper or enlarging the pathway would solve the problem.
Because fuel pumps used to be the common location of the problem, some folks now feel that vapor lock BY DEFINITION has to involve a fuel pump. We disagree, but that may be semantics.
Steve
Steve