here's a little trick. take the fuel hose off so the pump is free to move. tie it onto the cradle with a cable tie, but only tight enough so it wont fall off, but loose enough so the pump can move up and down with slight effort. now put it into the tank, and it should hit the bottom of the tank, and will slide up the bracket. then pull the whole thing out again, and move it up the bracket another few mm, pull that cable tie tight, and add ring clamps or whatever you're using to secure it (and the fuel hose of course). it should now be sitting just higher than the base of your tank.