Have a 2000 MERCURY TRACKER 25hp on a jon boat I bought about a month ago. Had the guy crank it up and run it for about 5 mins. brought it home and fixed up the boat for bowfishing and now it will not run. I can get it to run by spraying mixed gas in the carb but cuts off as soon as it burns off. replaced spark plugs, cleaned fuel filter, checked all the gas lines. Help please!?!