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Sandy Daugherty

Calibrating N2K sensors

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Will I need another instrument to complete the installation of two Lowrance N2K fuel flow sensors to be read by my Garmin GMI 10? Is there a calibration issue? Do I need a tank sensor?

7 Replies

  • Sandy, you don't really need a tank sensor, in fact it confuses the issues in some ways as then you have two ways you're calculating fuel remaining. On the other hand, if you don't have a tank sensor, you need confidence that the flow is being truly measured -- relative flow is not good enough -- and you need to be disciplined about inputing data when you fuel up.

    I'm 99% sure that you'll need a Lowrance guage or MFD to calibrate the flow sensors and to change one's "instance" so as to differentiate them. The Garmins, and others, can display the flow, calculate mpg, and keep track of usage.

    But since you already have the GMI 10's, why not get Garmin fuel flow sensors? Is my tendency to push the multi-manufacturer limits a bad influence???

  • I repowered with Yamaha 8hp high thrusts last year (and lost all of a half knot) but they burn barely one gallon per hour at wide open throttle, extending the range of my single tank The Lowrance meters are purported to read down to.6 gph or lower. The Garmins are not advertised to read below 1 gph. They are also available at $42 online.

  • And yes, you are a terrible influence. Shame, shame, shame!

  • I just rechecked: the GFS-10 is not advertised to read below TWO gallons per hour, and they are $200 apiece.

  • I surrendered, bought two Lowrance fuel flow sensors and a fuel flow gage. My excuse is that it fits a hole in the panel. So lame.

  • Sandy, I have the Lowrance fuel flow sensor working with Li'l Gizmo's 40hp Honda and 6 gallon tank. That's gotta be a pretty minimal situation, and though I've never seriously calibrated the system, it's giving me realistic flow and remaining fuel numbers.

    I hope you'll report back with your results. And maybe soon I'll get around to plumbing in a Garmin fuel sensor and see if it really is as insensitive to low flow as its specs suggest. It could be a case of under promising.

  • I had a very interesting time with our Garmin Area Sales Rep last week. I've been sworn to secrecy but I now will know exactly when Garmin comes out with a fix or new toy to deal with issues I'm concerned about. The answer is exactly two weeks after I bumble around, spend lots of money, and get a kluge fix almost working. This has proved true in the case of their N2K VHF, high def Radar, and 90 degree connectors for the big chart plotters. All became available AFTER I drilled holes, filled others and built a cantilever mount for my big display so it could sit on a 4" deep shelf. I also learned that the fuel sensors will read lower flow rates after a forthcoming SOFTWARE change, hence negating the need for Lowrance products. Keeping up with the Jones is easy; keeping up with Garmin is a whole 'nuther bank job.