I need to find a fuel powered 40 watt generator and I have looked everywhere and haven t found something even similar. Do they even exist?
That is a small generator. Most are far larger. Try a radio controlled plane store as a small engine like that hooked to a generator would do it.
The Oracle of Omigod
Perhaps you should consider a small Goal Zero Yeti generator which is charged by a solar panel. Check out Goal Zero.com
Check out fuel cells.
It would be inefficient to produce a low wattage generator powered by a fuel. The smallest gasoline powered is about this one https://www.amazon.com/Tailgator-63025-630253-Portable-Generator/dp/B00O39NQ96/ The current technology is solar charging and battery based or a hand or foot pedal crank. Cell phones charge on 5VDC, and need 4 to 8 watt hours. http://offgridpowerboom.com/best-hand-crank-generators/
Well that would be a very small genny The smallest ive seen is 1500..2000 watt,