I installed new fuel tank access plates with feed tubes and fuel return fittings in both tanks of the Monk. This allows me to plug the old fuel feed fittings located at the bottom of the tanks which is not good if those fittings leak or fail and fill the bilge with fuel.
Now I can select which tank to fed the engine and also select which tank for the return fuel to go back into, thereby having excellent control of fuel distribution between the two 30 gallon tanks. The Monk’s new Yanmar is burning less than a half gallon an hour at about 2400 rpm that gives me 9 kts, about 65% power. This with only 60 hours on the new engine. I’m very pleased with this engine and now I have at least 120 hours of fuel range.
Completed system
Both tanks have the bottom feed fittings plugged, two valves - one for selecting which tank to feed the engine and one valve to select which tank to return the fuel into. It takes about an hour to empty one 30 gallon tank into the other tank by feeding from one tank and returning to the other. Fuel consumption however is currently under half a gallon and hour with about 60 hours on the Yanmar.