Generac shutdown issues, help!

The fans are wrong, blow cool air in low, remove heat up high, you are pulling the cooling air flow down under the generator and out, trapping Heat inside, also the exhaust going down is just going to rise, some of it will even get pulled back into the covering box, optimal airflow is not being met with your current design, the carburetor might be too warm, causing a vapor lock, or the generator Head getting to hot and causing the engine shut down, sound reducing boxes can work when the correct design is implemented, sound mat is a good material , foam is not, egg crate or pin cushion foam reduces air flow and holds heat, many food vendors use inverter style generators on their trailers instead of open frame generators, inverter style are enclosed are quieter when running at lessor loads, if Honda or Yamaha is outside of your budget , champion and harbor freight have inverter models that are less expensive, you obviously need electrical power so it might be wise to look into replacing the generator , if not feasible, then redesign your box put the air intake in the bottom of the box with a fan blowing in, put exhaust fans on each end of the box , this will remove more heat than a single exhaust fan mounted too low trying to pull air thru and around the generator