I'm not sure but I think the fuel pump is mechanical so you have to turn it over to get fuel into the injection pump. It is most likely also a positive ground so be careful when putting the charger/boost on the battery. Be sure to have drained all the fuel bleeds, tank sump and wiped out the filer canisters etc. Mine had tons of crappy fuel, water and other stuff in the canisters when I got them apart.