My son add about 25 % diesel in the tank by mistake to make a small ride with my Polaris Sportsman 500 ho . He enjoyed for the first 15 minute the ride but after engine stall when he press the throttle .Start the engine , idle perfect but impossible to go forward . So je call me and I asked to stop at and take the trailer to back home

I remove the reserve gas line from the thank empty it clean it , wash it with gas ,dry it and plug the gas line .i also unscrew in the bottom of the carb the screw for draining bad gas , full up the tank with super unleaded gas .After this opération I reopen the carb screw to drain 500 ml of maybe bad gas in hoses , in case of. I close the screw .

I check spark plug .Veryy good fire

I start engine and RPM move from 1600 to 2300 for 5 minutes after running steady at 2100 . I reduce to 1300 and leave the atv running for 25 minutes on the idle . I tried to give some gas to increase engine revolution but almost stall.
I shut up engine and put back atv in the garage

I try again the next day . Engine run well at 1300 rpm but stall when I give gas . I try to leave engine stop for 10 minutes and when I start engine I press immediately on the throttle to see if it work because I thought if gas filter is partially blocked 10 minutes is enough to fill the carb thank ….but was not the case , so filter probably ok.

I also check in the throttle box if wire connect when I press the throttle but it is not the case. For share this problem occurred after diesel have been add to the tank

Thank you for help tips

Gas filter? Probably not
Fuel pump ???
Carb ?