I reckon 15A is too high. Reccomended is 10A for the fuel pump. The fuel pump wire is designed for 10A.
Best check out why your having to fit a 15A. You have bypassed the fuse, the fuel pump wire is not big enough to carry more than 15A......wire gets hot.......wire sleeving will melt and might result in a fire.
If the fuel lines are blocked then the pump is having to work harder, so the pump needs more current. Is the fuel pump getting hot?