I have't done a fuel pump on a Focus but have done in-tank pumps on another vehicle and it isn't too bad if you don't have to entirely drop the tank. I was able to partially lower the tank enough to get clearance to get the pump out. The other tricky part can be the ring nut that holds the pump in place. Sometimes it takes a lot of umpf to get these off and sometimes a special (or homemade) tool is required for that. You definitely want to be doing this on a near-empty tank, even if you are just partially lowering it. It is good that it is not the high pressure pump. Those things are really pricey.