Yes, wrong. It doesn't matter that the tube goes up and down. As long as no air gets in the system, it will not "lose its prime". What matters is that the pump is below the level of the fuel. Read about "siphon pump" (wikipedia, etc), a concept used for thousands of years. Test it. Remove the hose from the inlet to your pump and you should see fuel pouring into a pan. If it doesn't come out strongly, you have a restriction like a plugged tube or junk on the pickup sock. Most EFI pumps, like the Walbro external can draw fuel up > 5 ft with no problem, though if it was mounted above the fuel level you might have issues keeping it primed if there was an air leak.
