Blown Starter Fuse

I keep blowing the number 4, 30a, starter fuse. At the suggestion of a friend, I have already replaced the starter. The fuse still blows.

Installing a new fuse with the battery hooked up does not blow the fuse. Turning the key to the run position does not blow the fuse. Pressing in the clutch petal does not blow the fuse. Turning the key to the start position does blow the fuse.

What do I need to be looking at now to try and fix the problem?