Engine cranks but will not start

Truck was driving beautifully, was going up a steep hill and it shut off completely. I have been fixing and replacing various issues for the past month. First was the blower motor, then the ignition switch, and yesterday replaced the fuel pump and filter. Truck had no issues starting, running, driving. Today I was going to wire in a new trailer adapter, saw that previous owner had spliced into the rear light harness instead of using the trailer towing adapter wires, so I undid the mess and wired the rear lights like they should have been. Did not wire in new trailer adapter yet. Went to run an errand and that's when it cut off on me. Tried to start, engine cranks but won't start. First thought was the fuel. Pump, it is getting power and sounds like the pump is running. Truck will start with fluid sprayed into tb, then cuts right out. Was checking relays and fuses when I saw the horn fuse in the under hood relay box was blown, was not blown yesterday, so I pulled it and as soon as the blade on the new fuse touched the terminal it sparked and popped. I'm thinking a ground somewhere? Are my two issues related? I intend to try to chase it down with a test light, just stumped a little and could use some professional insight. Thanks in advance for your assistance!