Originally Posted by Deepsea21

That is a really interesting question. I think in all my cars the fuel pumps seem to kick in automatically for a few seconds when the key hits the on position before going to the start position. I figured it is because all systems are coming on-line at the same time so as soon as the key hits the on position on the way to the start position the fuel pump kicks in and the pressure monitor that tells it to turn on/off is also coming on-line at the same time. I guess I've never tried shutting down and then immediately turning the key back to the on position to see if the pump comes back on right away again or not. There has to be back-bleed and loss of pressure after a certain amount of time as there is no 1-way valve that opens and closes to maintain pressure in the fuel system after a shut down that I know of... It must lose pressure at some rate as the system de-pressurizes. Pressurizing a liquid is virtually instantaneous unlike air. I can't imagine any fuel system that is pressurizing liquid gasoline can hold it for long... We're talking about a few milliliters of gasoline getting pushed into the fuel system that develops functional rail pressure. I mean, take a sealed gallon of water and try to squish it... Ya can't.