Diesel crossover/running out of fuel

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  • #14736
    Ben McCafferty
    Participant

    Hi all, I’m a long time lurker, new member/poster. I’ve had 37-202 “nessie” for about 4 1/2 years now.

    We had an “interesting” problem last summer, that I’m wanting to resolve. I’ve done an archive search and also google, and am surprised to not really find any results on this at all. In short, we ran out of diesel mid-channel with about 40-50 gallons still in the tank(s). It was a perfect storm–most of the heavy stuff is to starboard (i.e. galley, me, etc.) and we had wind from the port side. Over many hours of running, it would seem that most of the 50 gallons had made its way via the crossover to the starboard tank, leaving the port tank dry. We were in the middle of the shipping lanes near SG in Puget Sound, and started moving everything we could to port. I believe I also used thrusters to spin us in place, putting the starboard side to the wind. We have a flybridge with full canvas, and that was enough “sail” to heel the boat a bit to port, and enough diesel moved across to get the main started, and we made our way directly to Shilshole marina for a fill up.  In this process, I also believe I recall seeing that the sole fuel pickup (in the port tank) is not at the low spot in the tank–but I can’t be sure.

    So–obviously I’m curious whether others have encountered this, and what solutions have been implemented with success! Maybe a transfer pump from starboard to port? Second pickup in the starboard tank? Etc.?

    We’re heading to Alaska next year, and while I’m hopeful we never need that last 50 gallons or so, I don’t want to bank on it.

    While we’re at it–I’ve been told that I was really luck that the main started again without having to do anything like priming injectors. Is there a good resource for how to restart after running out of fuel? nessie has the 380hp Cummins 6 cyl.

    Thanks in advance for any ideas!

    Ben

    #14744
    Gary White
    Participant

    Here’s one thought. I’m not sure how accurate it is because I’m going on various conversations from memory.

    diesels by the nature of their design don’t use all the fuel that goes through the high-pressure pump. Some of that gets returned to the tanks to be used again. If you’re boat has two tanks and there is no crossfeed open between them then the fuel returning would likely go to only one tank. Therefore as you drew down both tanks one would continually be adding fuel from the pump.
    again just a thought don’t take it as fact yet.

    #14745
    Ben McCafferty
    Participant

    Thanks Gary!
    There Is a crossover, So it is pretty small and cannot equalize during fueling for example. What you described may be contributing to the problem also. Perhaps I could reroute in the return into the port tank to help somewhat  with the issue

    b

     

    #14761
    Tom Easterbrook
    Participant

    Hi Ben,

    To the best of my knowledge, the port tank feeds the engine with the pickup exiting the tank right at or very near the bottom. Same with the crossover, but this is a smaller line. Gary is 100% correct, (at least for the 6BTA engine) in that the engine returns way more fuel to the tank than what it burns, and in essence is “polishing” the fuel while underway (takes about 5 hours to do the entire port tank?). The fuel from the engine is returned to the port tank.

    Balancing the boat is the best way to ensure that the fuel distribution between port and starboard tanks stays “equal”, or you could install a “transfer pump”. I suggest not letting your fuel supply get that low, and “top up” more often?? We travelled up the BC central coast and fueled up in Port McNeill, and even though not really needed topped up in Prince Rupert for the return trip and never experienced any fuel (shortage) issues of any kind.

    Personally, I closed the crossover when fuelling, but agree that it would not redistribute that fast as to be a big issue.

    Good luck,

    Tom Easterbrook

    formerly Pilitak NT 37-068

    #14764
    Ben McCafferty
    Participant

    Thanks for the added thoughts Tom! All good info. I’ll definitely be keeping the fuel level higher, but not being able to use the last 30-50 gallons “by design” is crazy, if you ask me. I do think a transfer pump is in my future–I’ll post again as I address this problem so others might benefit.

    #14782
    Tom Easterbrook
    Participant

    The pump might be a good idea, just remember, that if installed in the existing line, your tanks will no longer “self balance” (I expect when not running the pump would block flow), and the pump will have to be used to achieve this (so a person would have to remember to run it every so often), as well as there will be a slight danger of “overfilling” one tank should the pump be left running too long (with a spill possibly)?? Personally I like simple, as I am less likely to “make a mistake”, but I do agree with you about the potential difficulties of accessing the last bit of fuel (especially if your boat is not well balanced athwartships). Maybe purposely “adding” a slight list to port would help?

    Good luck with whatever you decide.

    Tom

    #14783
    Ben McCafferty
    Participant

    More good thoughts, thank you Tom! I’ll keep the thread posted as I get to this, and meanwhile will keep the tanks topped up!

    best, b

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