Motor issues

Ok I drove down to nacogdoches to purchase a 18ft sun tracker pontoon boat. I live in Mineola tx.The fella I bought the boat from got in it and cranked it up and I took it out for a drive with no issues. Brought it back to my house it sat for about a week. Took it out to the lake it cranked and stayed running for about 2 mins and died. And done it continuously until it won't start. It's gotten to the point now where we have to take the top plastic piece of the motor off and pull the throttle up and down while another person chokes it from the captains chair and puts it in gear and it runs fine while you drive it around. Untill you kill it and try to start it again. We've put new gas draining all the old gas out of it. New fuel filter. Ran sea foam through it. The motor is a 2002 Mercury 50hp. Any help or advice would be nice and very much appreciated thanks!

Carburated or injected? 4 stroke or 2 stroke? If it's carburated you could have some trash in your low speed jets, especially if it sat on this guy's place for a while. Others with more experience may have a better idea. If it's a 2 stroke be careful about running it like this, it won't get to warm up properly if you are high reVing to start it.

I believe 2 stroke oil injection

Find a mechanic in your area. May need the carbs cleaned if boats been sitting awhile

I'd probably look at Nautical Mile Marine and ask for Chris if your gonna go the shop route.

Fuel lines and primer bulb need to be replaced with ethanol resistant lines. older lines tend to deteriorate from the inside out due to ethanol.

Gman

Thanks for the help