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Fuel Gauge Accuracy

Discussion in 'Electronics' started by DOCKMASTER, Jun 22, 2021.

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  1. DOCKMASTER

    DOCKMASTER Senior Member

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    Good point, I didn’t see that part. I need to research these as an option a bit more. Thanks!
  2. Capt Ralph

    Capt Ralph Senior Member

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    Blame this on MBevins. He kept bringing it up the cruzpro stuff.
  3. Capt J

    Capt J Senior Member

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    The C18 engine computers are super accurate, just reset the trip and do it that way.......I'd also buy new senders. My guess is your senders are short because they couldn't wiggle the proper depth senders in their, given the ceiling height.
  4. mapism

    mapism Senior Member

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    I understand that in some cases dipsticks are not an option, but I guess you must have a pipe connection at the bottom of all your tanks, don't you?
    That's all you need to tee-in a sight tube, and then you can place it wherever more convenient for checking it out.
    It's just a matter of marking it later, consistently with the actual fuel level.
    Which is dead easy if the tank shape is regular, but also if it were larger/smaller along its heigth, since you have accurate engine displays, you could mark the tube consistently with them.
    Takes a bit of time, but you only should do it once.
  5. MBevins

    MBevins Senior Member

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    KUS make a Capacitive Level Sensor -CLS that is accurate to 1mm level changes. There are others as well.
    You couple this with the CruzPro and you get the accuracy. After you "teach" it.
    These have been around for over 15 years and for the life of me I don't know why more people don't use them.
    As I said earlier, I can look at my gauge and it tells me I needs 256 gallons to fill the tank and the pump kicks off at 256 gal. It's that accurate. Providing you calibrate it right.
  6. ranger58sb

    ranger58sb Senior member

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    Agree (although I thought they're in New Zealand).

    The "learning" mode is a bit fiddly. "Start with empty tanks..." isn't so easy to do with 500+ gallons of diesel on board... and smaller increments along the way gets old... but otherwise the FU60s worked very well. We mated ours with KUS/WEMA senders...

    -Chris
  7. Capt J

    Capt J Senior Member

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    On U.S. fuel tanks, it's fairly rare to have any pipe connections at the bottom of the tank. Generally American builders pull everything from the top of the tank, via fuel pick ups....... But in his situation with 3 tanks joined as 1, it would have to have hoses to each tank, but I'm guessing that they're too short to T a fitting off of for fuel level.
  8. Metatron

    Metatron New Member

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    You might try using a pressure transducer at the bottom of the tank(s). This should be very reliable and accurate. You will be measuring the hydrostatic pressure of the fuel above the sensor which can be directly converted to fuel level. There are many types of transducers available. You can easily get ones which screw into a 1/4 npt fitting either in the fuel outlet line or perhaps in a small hole drilled into the tank side at the bottom. You can get virtually any type of signal output but probably 4-20 ma current loop would be best. Basically, you want a sensor with a range of 0-5 psig or 0-10 psig. I suspect your tank pressure would be less than 5 psi.

    There are numerous types of display units available for 4-20 current loop.

    This is a bit of a write upon the technique. Or you can just google "pressure transducer tank level". This should be the most accurate and reliable method. You will have to calibrate it to fuel quantity when you fill up.

    https://www.te.com/usa-en/products/...nted-pressure-transducers-for-tank-level.html
  9. Capt Ralph

    Capt Ralph Senior Member

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    I recall Raritan had a strip to attache to the sides of synthetic tanks that could give rather good tank levels.
    Many years later, I wander if the technology has improved to measure thru metal (alloy) tanks.
  10. DOCKMASTER

    DOCKMASTER Senior Member

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    What type of senders and gauges are used by builders today? Viking, Spencer, Hatteras, etc? I don't want a science experiment or reinventing the wheel. Prefer something tried and true.
  11. Capt Ralph

    Capt Ralph Senior Member

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    Hatteras uses the ultrasonic stuff on their MYs.
    It's fair at best. Requires cleaning from time to time.
    They do have a good rythm programed in to it to eliminate wild reads when the fuel sloshes around.
  12. mapism

    mapism Senior Member

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    Well, every day is a school day, as the old saying goes.
    Thanks for enlightening me.
  13. rtrafford

    rtrafford Senior Member

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    FUS/WEMA....had to replace a full set of gauges after a lengthy direct voyage where the power was left on to the gauges (versus a momentary switch). Sometimes they are a little sensitive and not reliable as well. Sort of an ongoing issue that continues to be studied and considered. With belly tanks, there is no path to sight tubes, but perhaps I can see my way to some sort of above-tank tube with a float inside that could relay the level to a visible cylinder, sealed on top for odor, but tall enough to display the level. It would likely stick, too, from time to time, but it perhaps could be accessible with a removable cap to jostle the visual float and verify the reading. Thoughts in progress on this...
  14. rtrafford

    rtrafford Senior Member

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    ...but another thought is to similarly install an audible alarm with a full-sensor for tank filling purposes. One could fill the tanks and be altered to full levels prior to overflow. More thoughts to ponder.

    Generally speaking we keep solid hour and consumption/fill logs. We have a pretty good idea of what's going on in the tanks with or without gauge accuracy. Problem occurs when an event like a hose or prop fouling etc throws off your normal consumption understanding. You need the accurate backup.
  15. Danvilletim

    Danvilletim Senior Member

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    gen fuel avg I read was 1g per 10kw
  16. Pascal

    Pascal Senior Member

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    Probably accurate then of course the question is how much load are you actually using. That’s why I m ASSuming an average of 60% load

    on some Exumas trips we use more fuel in the gensets than the mains which could make calculating fuel a bit of challenge but I ve been pretty close