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Volume of returned fuel?

1856 Views 10 Replies 9 Participants Last post by  capecodda
I have a Yanmar 4JH2E. Curious if anyone knows how much fuel is returned to the tank? (And if anyone answers "all of the excess" I'll hunt you down and wind your furler backwards! :) )

The reason I'm asking is my boat has two tanks. I run mostly off the bow tank, fuel is returned to the keel tank. Just wondering if I need to be concerned about overflowing the keel tank with the return fuel.

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I would not return to a different Tank, it will overflow. The true rate of return has too many factors, line and pump size engine differences etc. it could be as much 95% or lower who knows. If you trust your Gage you can find out (sort of) but its tricky. A couple of three way valves can designate flow to and from individual Tanks.
I do fuel systems and Emergency Generators and its a big NO NO to mix Tanks. Plus the two tank tops may not be the same elevation and though unlikely you can get a negative siphon effect and overflow that way too.
BUT it sounds like you are doing it now, I don't know what the safety is but it would be good to know. Most systems return enough fuel to keep the fuel clean and "polished" with all that motion at sea. Yours may be designed with a much slower rate of return.
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