Fuel Filter Location

Pumps do a much better job of overcoming resistance to flow on the outlet than the suction side.* That's a big reason the in-line filter goes after the pump. There already is the 'sock' filter on the pickup itself, so the pump will not get any sizable dirt unless the line is rusty. Since the sock is large and fully submerged, its generally not creating any resistance to flow.

It's also helpful to locate the filter so its exit is higher than its inlet. This way any vapor pockets that form exit. You could see this on the aftermarket glass filter housings. On cars with vapor return lines, the concept is similar. Place the filter or vapor seperator so the exit to the return line is at the highest point.

*On the suction side the fluid will expand as the pressure drops. With gasoline, if warm, some portion may even vaporize.