Return fuel

  • October 30, 2015 12:43 PM
    Message # 3608145

    Is the return fuel line specific to a certain tank and need to return from the tank it came from?  Or will a common tee from the engine line return the fuel to whichever tank it is being drawn from. In other words do I need a shut off valve to the tank that is not being drawn from to stop the fuel from returning to that tank? The PO had a common tee but this does not make sense as to regulating the fuel to a tank. 

  • October 30, 2015 1:20 PM
    Reply # 3608207 on 3608145
    Deleted user

    Return flow should controlled and be valved back to the tank that's being drawn from.

    I suppose a common return to multiple tanks would work however you might deplete the selected tank for draw at a faster rate than expected. Uncontrolled, return flow will take the path of least resistance....

  • October 31, 2015 5:29 AM
    Reply # 3608840 on 3608145

    Ki use transfer valves to independently select which tank to draw from and which to return to.   I have always returned to the same tank, but in theory I could transfer fuel from on tank to the other by returning to a different tank.

    By the way, I just had my fuel tanks polished for the first time in 11 years.  The guys said my fuel was in excellent shape.  Zero sludge found, just four bees.  I use no additives.  I  have never found dirt in my fuel filters.

    The polishing guys said the secret is to use you boat a lot.  I run my engine about 800 hours per year.



  • October 31, 2015 8:57 AM
    Reply # 3608985 on 3608145

    You should absolutely return to the same tank you take the supply from.  If you return to the other tank, it may fill that tank, and the excess would go overboard through the vent fitting.

    That is why I always recommend installing the supply and return selector valves next to each other, so you can be sure of supplying and returning to the same tank. 

    KISS.

  • November 01, 2015 12:07 PM
    Reply # 3610096 on 3608145
    Anonymous member (Administrator)

    Alan:  

    Pygmalion has two fuel filters a Racor and a no-name filter, two fuel tanks and 4 fuel valves so you can control which filter and which tank you are using at any one time. the two filter valves are in the engine room and the fuel tank valves are under the galley sink. 

    Be sure to use CG approved fuel hose -- it's double thick for fire prevention purposes. 

    When the engine and tanks were out -- I now wish I had moved the overflow from the exterior of the boat to the interior - I know this sounds bad but so is dribbling fuel into the water with possible fines $$ -  at least you would know when your are overfilling or the overflow burps.

    Now it would be very hard to reach much less modify the arrangment. 

    Another thought is to add in the a  water vapor device into the fuel vent circuit - maybe a high loop for each tank then instead of running the vent line over board - combine them in the lazarret with a single vapor trap... 

    Bud - what do you think?  

    Jay

    Last modified: November 01, 2015 12:08 PM | Anonymous member (Administrator)
  • November 01, 2015 6:17 PM
    Reply # 3610429 on 3608840
    Deleted user
    Dick Mills wrote:

    Ki use transfer valves to independently select which tank to draw from and which to return to.   I have always returned to the same tank, but in theory I could transfer fuel from on tank to the other by returning to a different tank.

    By the way, I just had my fuel tanks polished for the first time in 11 years.  The guys said my fuel was in excellent shape.  Zero sludge found, just four bees.  I use no additives.  I  have never found dirt in my fuel filters.

    The polishing guys said the secret is to use you boat a lot.  I run my engine about 800 hours per year.

    Dick that's awesome.  Here's my story.  I refit new tanks.  In the interim I have been using 5 gal portable tanks.  New diesel often and in spite of that there was sludge in a short period of time in one of my portble tanks!?!  I was very surprised as I use my boat a fair amount and the tank is getting freshly filled frequently.  It sure convinced me to use additives in my permanent tanks that's for sure.  I don't know if you are lucky or my stations where I get diesel are crappy or condensation or?



  • November 03, 2015 7:31 AM
    Reply # 3613888 on 3608145
    Deleted user

    Hi Allen,

    We installed two new tanks that we acquired from Bud.  

    When we installed them we did a fairly simple plumbing arrangement with the fuel lines.

    We are able to switch supply and return and polish fuel by using just three 3-way valves and one filter.

    We always return fuel to the same tank when motoring but we do transfer fuel to one or another tank to keep the new fresh fuel isolated until needed.  It is a fuel rotation process.

    You can go here for complete details.

    http://www.captainmontgomery.com/search?q=dialysis

    Good luck.

    Last modified: November 03, 2015 7:20 PM | Anonymous member (Administrator)
  • November 09, 2015 7:14 PM
    Reply # 3625659 on 3608145

    I don't have an A/B valve for switching tanks so there is a T that connects the two before feeding into the Racor filter. The return line connects to another T that feeds both tanks at the top of the tanks. I don't like the idea of separating the tanks due to the weight imbalance (listing). I can still isolate either tank by simply closing the valve on both the top and bottom of the tank, but would only do so if I somehow deducted that one of the tanks was delivering bad fuel. 

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