hey guys i just came across this post, i just had a customer drop a machine off at the dealership with this issue recently.
lights worked, brake lights worked but no power to meter, fuel pump or ignition circuit. i started by checking the fuses, all good. Then started checked for power on each fuse. Ignition fuse only had 1 volt on it. traced the black wire out of ignition fuse to the igntion switch which is powered by a red wire. this red wire splits off into multiple places such as regulator, main power relay and the diode in the fuse box. the reason why it will work if you jump power from red black wire to red wire on main power relay is because your simply borrowing the power from the red black wire to jump the red wire circuit. which is fine until the wires on the red circuit contact where ever they are broke, then youll have back feeding issue. i started to ohm out the wires when i noticed no power sitting on the red wires at any of the ends. Everything checked out til i got to the diode wire in the fuse box, about 8 inchs down from the red wire on the diode in the fuse box was a tiny 1\8th break in the line. I soldered a new wire in between the breaks and everything started working again. I hope this helps some people. Remember you should have power sitting on red wire going to regulator with key off, should also have power sitting at red wire at ignition switch and the main power relay.