plumbing on auxiliary fuel tank

[seabreez]

Originally Posted by rwidman

Don't forget that your engine uses less fuel than the pump delivers and the excess is returned to the tank(s). Don't get yourself into a situation where the return is pumping into an already full tank.

I just quoted and forgot to mention the return lines. We had two fuel tanks with one water/fuel separator and the fuel return lines were to my surprise connected together until one day we had a huge mess on deck... to find out that the setup was pumping from one tank and returning in the other tank until t got so full that the fuel was coming out the vent tube deck fitting (on a tug). since then they are now separate with individual filters. Peace of mind.

[seabreez]

Originally Posted by sck5

I put an auxiliary tank on my boat. I left the original main tank just as it was with its own fuel fill and with the fuel return from the engine going to it. The new aux tank had its own fuel fill and a transfer pump to send fuel to the main tank. That way I always filled the aux tank and then pumped the fuel to the main tank so it stayed fresh and wasnt sitting in the aux tank for a long period of time. Transfer pumps are cheap and make it very easy - Just press the button and fuel goes from the aux tank to the main tank until it is full. Then turn it off. Very easy.

Many ships are setup that way and will transfer fuel from storage tanks to day tanks and will only pump in what is needed for the day. They can minutely monitor what is being used and can manage the fuel burn better and order exactly what they need when they resupply.

[Frankly]

One other advantage of plumbing the aux tank to the main is then you can run the aux tank to complete empty. If you are drawing from two independent tanks you are forced to leave some behind because last thing you want is to try, running on air.