Champion 3100W Inverter/Generator...run 15K AC on Propane?

I have the 3400 watt and it will start the AC and run it on propane with everything else off to include lights and the frig running on propane. If I start with gas, everything else is good on electric minus the microwave. So I would say a 3100 watt would not start it on propane (maybe with a hard start capacitor on the AC). Now, I have not tried either gas or propane in higher altitudes.