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flo scan problems

Discussion in 'Technical Discussion' started by Capt Ralph, Feb 22, 2014.

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  1. Capt Ralph

    Capt Ralph Senior Member

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    Got a flow bug. Hoping somebody has already been here. Thru many years my flo-scan system has worked well.
    Now,
    Stb 12v71ti reads way low on fuel use. Last weeks run under loads showed the stb using fractions of fuel compared to the port engine. Friday night I started looking into it.
    In the diagnostic mode the return sensor flows more than the feed sensor at idle resulting in 0 consumption idle no load. the port main varies between .5 to 1.5 gph idle no load.
    During my no load testing, the flows on all sensors bounce around a good bit but after watching them, an average comes to you.
    Yep, all filters changed and same low vacuum between the engines.

    All of the sensors are averaging about the same but the stb return. It flows more.The stb return sensor is showing more return, how is that possible?

    I started this last night. Found the trouble shooting guide and have been going over it. all checks out. I can also swap displays and the problem stays to stb. All switches to default, 0 (except tach switches).

    Anybody been here?
  2. Capt J

    Capt J Senior Member

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    Yeah, change the filters on the floscan, it should have an inline filter or at least the ones I've played with have. You also have to take the sensors apart and clean them.
  3. Capt Ralph

    Capt Ralph Senior Member

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    Just back from the bilges.
    It is a PITA to remove the sensors for cleaning, I did the best south Georgia cleaning I thought of;
    Drained the racors, removed filter, removed the fuel in line to the racors, removed the out line from the first flo-scan (fuel in) sensor. Blew in/out lots of air. Figure 90 psi @ 8 to 10 cfm, for several minuets. When compressor tapered off, charged up and did it again for several attempts.
    Pulled the return line off the fuel cooler, (Detroit's cool the fuel on the return side), blew air thru as above. This would give the return sensor a good,,,, blow. Can really hear the fuel bubble in the forward (low on fuel) tank.
    So, I feel good the sensors are mostly clear. Charge with fresh fuel (another new filter), after 15 minutes fast idle, same problem. Return sensor spinning faster than feed sensor.
    Were only talking (no load) approx 1 gph error (drops in a buck error) I have NOT changed any symptom.
    Oh, while charging with air, no leaks detected. All fittings are still bone dry. Would figure if any joint leaks, a fitting would get a lil wet if blown a little (works for me).

    I'm on to the rum...,
    rc
  4. Capt J

    Capt J Senior Member

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    I think the sensors have a wheel that spins in there and if algae gets on 1 or all of the blades it messes it up. How does it read when you're consuming more fuel?
  5. Capt Ralph

    Capt Ralph Senior Member

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    Under load, the stb shows to start using fuel, @ cruise, near 1/3 of port eng consumption. Port eng is correct.

    Was hoping a blast of air would clear anything on the paddle wheels. Oh Wel....
  6. bobhorn

    bobhorn Member

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    Have you contacted Floscan tech support? They have been very responsive when I have contacted them. Usually reply the same day.

    Bob
  7. bobhorn

    bobhorn Member

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    One more thought. I think they are turbine sensors, a little wheel that spins. Blowing compressed air through them may not be the best idea. It makes them overspeed and there is no lubrication for the bearing.

    Bob
  8. x-fire

    x-fire New Member

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    I have an issue with my sensors, and I think floscan went belly up
  9. Capt J

    Capt J Senior Member

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    I'm pretty sure they did. Of all of the boats I've run with floscans, I've hardly ever had a set that worked perfectly...….most would not read anything under 1000 rpms (light consumption), or not read at all or whatever.....I always just calculate my burn rate based on RPM and propeller curve chart.
  10. x-fire

    x-fire New Member

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    I am getting low readings, about 50% of both engines, I was hoping to find a set of directions for cleaning or the 20B replacements
  11. Capt Fred

    Capt Fred Senior Member

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    Capt Ralph: Two thoughts, It appears to me the most likely problem would be the in fuel sensor reading too low ( clogged with algae, bad bearing) or an electrical connection causing the out flow to read too high or the in fuel to read too low. Between these two thoughts the most likely would be the in fuel sensor turning too slow.
  12. Capt Ralph

    Capt Ralph Senior Member

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    You know your tapping on me for a 4 + year old thread.

    I had two problems thru the years. One sender did fail and was determined bad by the diagnostic with no pulses or signal and knowing the wheel was turning.
    My second problem was when a wheel was turning slow. The wheel was covered with a water/diesel snot and after cleaning, still required many hours to finally clear out with fresh fuel and tank cleaner.
    I have another thread with this water/fuel/snot problem.

    LOL, at one time, my flow meters were showing I was making fuel.

    My flow scans were never accurate and never will be (god knows I have tried). But they are a tool to use to help avoid problems.
    When you start in the morning, make note of the flow, if it changes rapidly (+ or -), there is a problem, go below and check your low pressure (VACUUM) gauges.
    Use the factory fuel flow graphs to plan your day, never your flowscans.
  13. Capt Fred

    Capt Fred Senior Member

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    oops, my bad
  14. Capt Ralph

    Capt Ralph Senior Member

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    Not a problem. Probably needed to finalize the thread anyway.
    I don't think you can see the date on a phone or pad anyway.
    Only so much stuff you can put on a lil screen.
    That's why I still luv my large desk top screen.
  15. x-fire

    x-fire New Member

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    OK,
    With the good old fashioned country boy attitude. Meaning they were not working so what do I have to loose? I pulled the sensors one at a time. I did one then tried it and did the other one. There are 4 bolts holding the unit together. Remove them and give the body a whack with the handle of the nut driver to loosen the cover from the body. Very carefully remove the diaphragm from the body. Use extreme care you will need to re-use it. You can easily figure out how they work and how the flow of fuel runs through the unit. Use a good grade of cleaner like gumout carb. cleaner. Spray it into the chamber where the well is. You cannot see the wheel. It is sealed. Flush it out several times. Fill the chambers with your cleaner and let set for an hour or two, keep adding cleaner as it evaporates. After it has dried out use a product called tri-flo, it is a teflon based lubricant/penetrating oil. Let it set for 5 minutes, pour out the triflo and re-assemble. It worked for my sensors. A word of caution, be extremely careful removing the diaphragm, there are no replacement parts.
    I would not spray cleaner into the unit till you have removed the diaphragm the cleaner most likely damage it.
  16. x-fire

    x-fire New Member

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    BTW, they read flow at an idle, goose the engine and they spike up quickly now. How long they will keep working is anyone's guess
  17. Capt Ralph

    Capt Ralph Senior Member

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    Diaphragm? What model sender were you working on?
  18. x-fire

    x-fire New Member

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    it is a 264 for gas engines
  19. Capt Ralph

    Capt Ralph Senior Member

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    Oh, small sender. Pulsation dampener. I'm on page now.