82 750 seca turns off when I sit and other electrical issues

Hey all-
Since I tried jumpstarting from a running truck the bike won't hold a charge or start without a jump from a car battery. I've started and ridden my bike a handful of times but noticed the last guy deleted the fuse box. I just installed one ( first pic) in hopes this would make it able to start independently but no luck. While tracing wires I also found what looks like a blue sensor wire (second pic) tucked behind the frame tubing underneath the seat. No the bike shuts off when I sit down.
I'm hoping for input on why it's not holding a charge or what that sensor is before I strip this thing down and rewite everything.

 

Your fusebox looks fine; good work.
The blue thing is the battery electrolyte level sensor, and has nothing to do wih your problem. It can be addressed later (you will have a battery warning lamp illuminated until the sensor is hooked up).

That the battery can't hold a charge is indictive of a faulty battery. Remove it, take it to an auto parts store, and have it load tested. If the battery came with the motorcycle, it's safe to assume that it needs to be replaced. We can continue to check the charging system once you know that you have a good battery.

You should take a look at the links in my signature, particularly the first one.

 

Thanks for quick response. Ive read through a lot of the first link but went through some more today. Battery was at zero charge and is charging at advance auto overnight so they can test in the am.

 

I moved my fuse box put seat on sat down and it killed my power. moved fuse box back problem solved

 

Battery was definitely bad. Replaced with last one in stock at battery and bulbs. Wondering if there is a good thread on XJ about compatible batteries or possibly even old school acid batteries.

Checked my fuse box location. Small registration/tool compartment in seat was pressing down on fuse box and the main power wire was disconnecting slightly.
Solution: place wires more flush with intake cover, used channel locks to tighten the female connector for better fit with fuse box.


Now almost everything works! Blinkers are working, starts with one push. I also changed the petcock which helped with some other issues.
However, the center instrumentation display is not functional. Found this pic on google, not my bike but cool to see working for the first time.
http://4.bp.blogspot.com/-kb-7tXo0PuQ/TjTLpQo1D2I/AAAAAAAAAEU/HhIice5PUNc/s1600/atari.JPG

Basically all the warning lights do not light up and the check/warning buttons do nothing. Neutral light works, high beam light works, and I forget but I'm pretty sure the dash illumination works. Another weird thing is the horn sounds like it's struggling to make a sound unless I have the battery connected to my car. In fact everything seems just a bit weaker than when connected to a car battery. Maybe just needs to run for a little while to shake off the dust? Or bad stator which I'll need to research and learn electrician stuff about so I can finally understand all the threads about resistance, ohms, and other mystic motorcycle mechanics.
Thanks for responses guys. Solved everything I asked about. I know this stuff is obvious to most but I'm a truck guy and bikes make me second guess all the basics.

 

the center instrumentation display is not functional
atarti package could be you need polarized film to pot over it got any polarized sunglasses?
there are a few posts on this
Computerized monitor wiring
could be it has to be reinstalled

Breakdown of the 750J Gauge Cluster