After the pump has pressurized the line, the pump regulator kicks in and senses full pressure and starts shutting off the pump. And I don't think you can just remove the fuel line at the injector, cause it should sence low pressure and shut the pump off then as well.
Just unplug the elect. connector at the pump and see what the voltage is, should be the same as battery voltage.
for testing purposes, you really need to rig up an inline pressure gauge, any ol' cheapy pressure gauge will do as long as it can handle petroleum liquid and goes to at least 50 lbs. I think minimum test pressure is 38 lbs.
Check all your connections and make sure they are clean.
'08 Sportsman 500HO efi
'14 RZR 800 trail
'03 sportsman 500HO (gone)
'14 Massimo 800
'08 Hisun 700(gone)
'02 expedition 425(gone, but missed)
'98 Sport 400 (gone)