Help! Onan 4K generator refuses to start and stay on

Target is the big red store?
Never heard of that fuel cleaner but I'm also just a shade tree mechanic. Maintaining my own trucks and small engines. I use startron but it gets horrible reviews on YouTube.

Might switch to Rev X. Any opinion on that brand? I've bought their oil additive for my 7.3L diesel. Expensive stuff. My buddy told me he recently became a dealer for them. So I might try their fuel stabilizer for small engines that sit for months.