Ford F-150 - 1997-2003 :: 1999 F250 - No Start / Low Voltage At Inertia Switch

I bought this truck and have been working on this problem for two full days. It has been sitting for over a year and was told it needed spark plugs and a battery. I replaced both items and it turned over, would start with starting fluid but only briefly. I disconnected the fuel line on the tank side of the filter and had my son turn the key on several times, no fuel. I reconnected the line and tested voltage at the tank (Pink and blue (+) and black (-). No voltage.

I went to the fuse box under the hood and have good 15A fuse with 12.5V there with the key on. The relay also makes 3 audible clicks when I turn the key on. I tested the inertia switch green/yellow wire; 6.8V grounded to the truck or to the small brown wire. I looked at the condition of the green/yellow wire up and into the harness and it did not appear damaged. Where this green/yellow wire travels to? I had read that it goes to the fuse box inside but did not see a listing for this in the manual.

1999 F250LD 5.4L Auto 4X4 142k