If it just sat for three weeks without being on a tender, there could be a power issue. Low voltage can make them run like that and yes, still have enough to crank it over. Also, common for many is the main fuse holder...not the fuse itself. That's the one in the back compartment under the driver's seat. Bad internal crimps make for bad connections without blowing the fuse. Ok...what else. Take the gas cap loose and try it. The tank check valves tend to dry out and stick shut sometimes. Also test the fuel pressure and volume. The filter or pump may have an issue. Another thing...and I just ran into this one myself, is the dash switches are NOT water proof. Just resistant so they can get water into them and corrode the contacts...I an alluding to the kill switch as it kills or allows power to several systems. Other things can also do it...one is low compression or leaky valves. Might check the valve lash and take a compression reading. Hopefully for that 1200 miles she had a good Unifilter on it and not the stock paper filters. Otherwise that's about the life expectancy for one using the OE filter.