A parallel plumbed system will always have some bit of assymetry which will cause most of the fuel to be drawn from one tank. And the same lack of symmetry will send most of the return fuel to one tank, but not necessarily the same one.
No. Depending on the engine the fuel return is usually much more than the fuel burned.
While I *can* select to to and from tanks on my manifold, I never do. I draw from both and return to both. It always seem to burn almost even from both tanks. If one gets a little ahead, the other catches up shortly with no intervention from me.
When travelling where fuel could be suspect...many operators will only fill one side at a time and run from one side. That way if the fuel is bad, you have options...
That said I have never gotten bad fuel in the states or Bahamas for over 50 years of boating. But I have heard horror stories including a friend of mine that flamed out both helo engines between the fuel truck and the runway due to 20 gallons of water!!!
Assuming a vessel is sitting level port to starboard, with port and starboard fuel tanks, should you have the fuel selector set to take fuel from both tanks to maintain trim?
Tom
Do you keep another tank ready for the lobsters??
.............. I see where the fuel goes from the top of the tank to the RACOR, ......