Sometimes you can create a vacuum in the fuel system which will starve the pump/carb. Unscrew the fuel cap, if it runs then there is a problem. First, check the gas cap, they are cheap to replace. Second, check your evap canister (if you have one), if its plugged then that will create the vacuum. Run a hose from evap steel line straight to carb. If it runs, then it is a bad canister. Finally, check the return lines (if you have them). One could be collapsed.