I don't want to be a wise a$$, but, just to clarify things, this would show a vacuum leak not press..Pressure leak would be on the outlet side of the pump. is this not true ?
If you are checking for presure leak, you will have to put pressure in the fuel lines, from tank pickup tube to end of hose that connects to fuel pump. One mfg recommends 15 inches vaccuum, 15 lbs of pressure. You will be supprised how many high priced fuel filters leak.