I thought I might share a discovery I made on my Onan 5500 in my Fuzion 404 Chrome. The generator would run excellent when first started but would start to surge after fully warm. On hot days with the AC on it would stop. After a cool-down period it would run fine again. I did the usual small engine routine, drained the fuel and replaced with fresh, cleaned the carb., new plugs, a good cleaning, etc. The next weekend out, it did the same thing. However on a cool evening it would run as long as I wanted. Today my new fuel filter arrived. When changing that, I noticed the rubber fuel line had a pretty sharp kink where it was crimped on to the filter. But the hose felt stiff enough that it wasn't starving it for fuel at that point. But I wondered how the hose felt when hot.
So I fired up the gen. turned on the AC's and let it run until it shut itself off.
The fuel line was quite soft and pliable now and was hanging at a near 90 degree angle off the filter. It definitely was starving the engine now. I replaced the filter and trimmed the line back a few inches and supported it with a few zip ties. It's still going after two hours on a hot day with both AC's running.
I think I maybe have it solved.
Just something you might want to check if you are having similar problems. I think just supporting the hose might have solved it. But trimming back past the bent area and a new filter can't hurt.