30 amp ignition4 fuse blows when turning key

So does the fuse blow in the start position or the run position?Also do you have a manual or automatic transmission?

Keep me posted does it blow right away as soon as you turn the key to the start position?You probably have a shorted wire or a bad starter.

Its really easy to see if the ignition switch is keeping the starter on. Test for power at the yellow wire to the ignition switch then turn the key to the start position you should see power then turn it back to the run position the power should shut off to the yellow wire. This test will only work if the starter is staying on the yellow wire at the ignition switch should only have power with the key in the start position.

I already told you how to test the ignition switch why did you change the switch without testing it first like I told you?Also while the starter keeps running without the key being in the start position see if there is power at the small purple wire to the starter. If you do then bad starter.