2007 Cummins Onan 5500 marquis gold gasoline generator

When you open the choke it increases the air flow but the gas flow is insufficient to maintain a proper fuel mixture; the mixture leans out and the engine quits. My guess is there is a clog somewhere in the fuel line or in the carb. One thing we used to do with cars was to blow out the fuel line to the gas tank with compressed air. Clog could also be caused by clogged jets in the carb.