I recently purchased a 1978 Mako with a 350 GM inboard engine. This boat has two 36 gallon fuel tanks. I have noticed that when using the boat the engine is only pulling fuel from the left fuel tank. I can close the feed valve from the left tank and fuel will then pull from the right tank. I have started with two fully filled tanks and run the boat until the left tank reads less than 1/4 tank and the right remains full. I think that I could completely drain the left tank if I allowed this to happen. I checked all fuel lines and there are no leaks or locations where it looks as if I could be loosing vaccum. Neither tank has a anti-siphon valve as I thought maybe I may have one with a stronger spring and although I know I need to install these valves it is not the location of my feed problem. Each tank has basically the same length of hose leading to a single fuel/water separator and then just a single supply line to the engine fuel pump. Both tank vents have been checked and are free of any obstructions. Back in the 1990's I owned another 1978 inboard Mako's and both tanks in that boat fed evenly from full to empty. I know that this problem is controllable by closing the feed valves but I would like to get both tanks feeding evenly if possible. Any suggestions would be appreciated.
