When checking a vehicle with starting issues,(failing starter) the acceptable current draw from a starter is 250A. I have tested alot of starters, an electrically "good" starter will typically draw 50-180A. When testing an electrically "bad" starter (one that stuggles to turn over) your amp draw goes 250A+ . I would say that you would be safe using a 250A fuse. The only time it should blow, is when the starter starts to draw too much amperage.
