so my 2005 E250 5,4L seems to have developed a fuel leak and the top rear of the tank. it only seems to leak when the tank is full, Anyone run into this before i pull the tank out?

 

Do you have a CEL related to EVAP? Check just the filler neck first without removing the whole tank.

 

no CEL if its the filler neck wouldn't it leak at the front of the tank?

 

Some tanks have the filler tube connected at the top end of the tank.
A lot of them get corroded and leak there.

If the leak is present some of the time, it could involve the top of the tank ,if all the time depending on the level,trail could be misleading.