I never heard of a Briggs motor on an Eska leg, it's likely a two stroke Tecumseh engine. Post a model number. Look about halfway down the leg on the port side, and if there's a little oval plate held in by two screws, there's a linkage adjustment under it. Loosen the adjustment bolt with th e lower unit in neutral, set the lever in neutral position, tighten adjustment bolt, and see if it outs the lower in gear.
While it's running, try turning the bowl screw in, and see if it lights up and starts running better. If it does, turn it in till it starts running lousy again, then back out to the mid point between too far out and too far in. then with it idling, do the same with the side screw.
If the on board tank line has a shutoff, make sure it's closed. You don't want the fuel pump element trying to pull fuel from both tanks - The onboard tank is vented, too, and any air that gets in the line ain't fuel.
