Fuel valve what the hell for

[jfkal]

Always made it a habit to close the fuel valve at the tank until I changed the secondary fuel filter....... Shut off the fuel dutifully just to discover that after removing the secondary filter fuel was happily flowing supplied by the return line.
Production boat needless to say.
Feel like an idiot going mentally throught the exercise shutting down the fuel in case of an engine fire. What a surprise that would have been then.



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[snowleopard]

care to share with us which production boat? of course the return line should go to the top of the tank thus avoiding syphoning.

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[AndrewB]

<blockquote><font size=1>In reply to:</font><hr>

<font size=1>of course the return line should go to the top of the tank thus avoiding syphoning.</font size=1>

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... maybe they've accidentally fitted the fuel stop valve on the return line rather than the fuel line!


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[jfkal]

JEANNEAU !@#$%^&*()

Both go right to the bottom (1inch above) of the tank.

GRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR..



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[AndrewB]

This could be to counter foaming. Check if there is a blocked anti-syphon hole or valve in the top of the return pipe inside the tank. A simple remedy would be to create one.

 

[Col]

I have stop cocks on both flow & return. Can you not retrofit one?

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[jfkal]

Will do so once the tank is empty next time.

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[jfkal]

Okay. Now, what if---- I forget to open then return line valve. Major disaster ??!

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[AndrewB]

Depends ...

... on whether you count the engine shutting down as a major disaster. It gets very unhappy first, chucks fuel and black smoke, which might jog your memory. I had a blockage occur in my return line, and the pressure caused leaks around the injectors which needed to be sorted, but it wasn't too serious a problem, washers needed replacing.

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[uforea]

On boats that I have owned the fuel return has always gone back to a filter housing and I always thought this was because you did not want warmed fuel going back to the tank as this encouraged the dreaded Bugs!!!!!!!

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[jfkal]

That is true but the oversupply returned is always a lot more than the engine consumes. So there is always warm fuel going back to the tank for the benefit of the bugs. Question is what happens if I do not open the valve for the return line?
Engine runnaway, explosion, fire?

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