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Volume of returned fuel?

1854 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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For any given engine several factors determine returned fuel volume, engine speed, load, piping details and lift pump condition to name some.

If you really care to know what yours is it can usually be checked....get everything ready.... disconnect return line at a suitable point, start engine and flow fuel into a clean 5 gallon bucket, filling a clean "calibrated" container, say 1 quart size, and emptying it into bucket as you go. measure time taken to get a quart, you can work the rest out from there.

In my engines (Cummins 6B) it is close to a gallon a minute +/-

Returning to a T in the fuel suction line is generally not a good idea, main purpose of the fuel return is fuel leads generally to injection pump failure.

The returned fuel has passed through all your fuel filters, putting it back to the tank also helps clean up the tank contents.

You should always return to the tank you are drawing from, exception can be made if you are using the system to transfer fuel under close observation, or if there is tank levelling through some piping arrangement...but generally keeping tanks separate is a better option.
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