I just bought a boat that has a 1991 Evinrude intruder and the boat has 2 gas tanks that are on the back of the boat and it's not a removable tank, they are built in the boat. Where you put the nozzle for gas, i was wondering do you mix the gas where you put the gas nozzle in.? All i have ever had is the one's that you can take out of the boat and mix the gas. Thanks.!