Re: Fuel Tank not accessible and have to drain bad gas on 5.7 Mercruiser
This was originally for removing water from the fuel, but you can empty all the water and old gas using the same method.
Head to your local auto parts store and get a cheap electric fuel pump. Make and model doesn't make any difference. Pickup some fittings for the pump so you can attach some 1/4" ID clear tubing to both ends of the pump. Then get you a couple of feet of copper tubing that will fit tight inside the clear tubing, and put it on the pickup side of the pump. Make the output hose long enough to go into a container for your junk gas.
Put some wires on the pump (a red and black will work..... red for positive and black for negative) put some clips on the end so you can hook to a battery.
Since water always settles to the bottom of the tank, raise the bow of the boat so the back of the tank is lower than the front. The water will also head to the back.
Then remove the fuel pickup tube from the tank (make sure the fuel level is low enough when you start that it doesn't run out of the fitting when you pull it out).
Start your electric fuel pump and stick the copper tube all the way to the bottom, move it around and you will get all the water and leave the gas.