You may want to go directly to the gen and prime it there and make sure you are hearing the prime, you could also pull the fuel line and see how long it takes to for the fuel to get to the carb.
Another thing you may want to start using Ethanol fuel treatment in the rig, I know first hand that todays fuel eats away the Onan carb parts, as I just sold my last Toy Hauler that after one time I missed using the fuel treatment it got gummed up and wouldn't start.
__________________
|