What to do about old, dirty fuel

I have a '01 XJ that has been sitting for 4 plus years. It was driven once 1/4 mile in the middle of it's lawn ornament career. Now for the issue/question. It has a minuscule amount of fuel that has been in it this whole time. The fuel looks as though it belongs in a coffee cup instead of an engine. This was the fuel that it used to drive the 1/4 mile so it has been carried through the engine. What do I do with it? I don't want to try to start it with that in there if it can hurt the engine if it didn't already or more so. Should I add fuel (how much?) to "dilute" the nasty and try to start it? Should I add fuel and Seafoam (again, amounts of both) and try? Is my only option dropping the tank to empty and clean it and if so do I need to clean the whole fuel system too?



Sorry for the length but I'm trying to give all the information I can for you. Any help, options and ideas are greatly appreciated!