My 2-year old "Deluxe Garden Tractor" 917.287500 blows its fuse when starting. Engine runs after starting, and until now the PTO worked too. Unfortunately, the PTO has stopped working as well.

Here's what I have done:
1) Checked ignition switch: fully OK.
2) Checked wiring for shorts or loose connections: OK, including under engine shroud.
3) Disconnected PTO connector & started engine: fuse blew anyway.

Now what?

Thanks for your help!

Hi,
Your manual was available, but had no schematic or parts breakdown. However, the schematic is available on searspartsdirect.com and is attached.
From looking at it, the most likely source of your problem is the keyswitch since the fuse is protecting the current flow going to it and the rest of the harness. It has multiple circuits and one can work while other fail. This is assuming that you did not overlook a bare wire, fuel shutoff solenoid would be a place to check.
The switch is made by Delta and can probably be obtained competitively.
Peace,
Clarke