Electrical triple problem.

Hello. I'm battling rust at the end of Jimny. Today I had to go for the first time with a car and suddenly triple problem occured at the same time. 

Onboard clock died, radio is working erratic (sometimes it turning off for a moment then come back, I can't change radio station because it will restart itself) and my fuel gauge is not coming down after I shut off engine. It seems its showing proper amount of fuel, it went down a little after long ride. 

Can those things be connected? Everything worked good before. Ofc I didn touched any electrical stuff and working only at the rear of vihicle.

The fuel gauge shouldn't drop when the ignition is off, so that's fine. I think the radio and clock share the same fuse, so the issue is connected. I'd pull the radio out and check any connections there, as that is the part of the wiring that is most likely to have been tampered with.