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"Full" gas tank only showing 81% full

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  • "Full" gas tank only showing 81% full


    I have a 2018 X23 that I've only had out a few times so far and I add gas manually with a siphon from a 25L (6.6g) gas can. Filling the tank today (from 68% full according to the gauge), the tank started to overflow which I assumed meant the tank was full, but when turning the key on, the fuel gauge only showed 82% full. I have the fuel management feature disabled.

    Is it possible that too much air got into the tank via the siphon and it's messing up the fuel reading? I added roughly 80L (21g) of fuel before I got some gas overflow and I'm pretty sure I had more than half a tank of gas left (the 68% reading seemed about right), so I'd expect the fuel gauge to read closer to the mid to high 90's or even 100% full.

    Is there something I should check? When I look in the gas fill hole on both sides of the boat, I can clearly see fuel.


  • #2
    Not a trapped air problem. The tank vents out if the top. It has a capacitance based sending unit if you have a gauge, no moving parts. If it is suddenly not going to full, it may likely be a bad sender. Try disconnecting the batteries and then reconnect. Should never have to do that.

    All that said, which dash do you have? Dual screens or analog gauges and side screen?
    There may be better ways to relax than being on a boat...I just haven't found one yet!


    • #3
      Since you’re mentioning actual percentages I’m thinking you have dual screens and you have to tell the system how much fuel you added.
      There may be better ways to relax than being on a boat...I just haven't found one yet!


      • #4
        I have the dual screen setup, but I have the "fuel management" feature disabled. When fuel management is enabled, that's when you specify how much gas you've added, but when disabled, the system is supposed to rely on just the fuel guage and doesn't ask if fuel has been added.

        I found this in the manual:
        To ENABLE or DISABLE the fuel management software:
        • Navigate to the Main Menu tab.
        • Tap SYSTEM SETTINGS.
        • On the system settings page, select either ENABLE or DISABLE under Fuel Management.
        Disabling the fuel management software will allow the fuel gauge to read fuel levels directly from the sensor on the fuel tank. You must reset the sensor when disabling fuel management. To do this, cycle the battery switch ON then OFF. With the key switch OFF, fill the fuel tank to 100 percent full at a fueling station. Turn the battery switch ON, then turn the key switch back ON.

        I think my issue lies in the steps there; I didn't reset the sensor as you stated. I'll have to try that then and see what happens. Thanks for the tip, I think that might be the issue here.


        • #5
          Well, still showing mid to low 80% after following the steps in the manual. Perhaps I'll try again the next time I fill the boat and see what happens.... or I'll just resort to enabling the fuel management function. Seems weird though.


          • #6
            My 2017 does the same thing, and it literally never goes above about 80%. I've never had an MC with an accurate fuel guage though, so I have been overlooking it. Post back here if you figure it out!


            • #7

              Making boomers great again!! Boomin'


              • #8
                Everyone hates on the fuel management system, but there's a reason they add it. 50 years later they still can't get a working gas gauge, and they know that.
                2020 Table Rock Mastercraft Reunion Poker Run Champion

                I lead the fight to ban the swimsuit thread, help me bring it back:

                "LDA never saw a thread he couldn't run off the rails"


                • #9
                  Originally posted by CantRepeat View Post
                  Thanks kinda funny
                  2014 Chap 264 Sunesta
                  2019 XT25 GEN2 5500
                  2015 X20 SS GEN2 6.0
                  2016 G21 Coastal 5.3
                  2014 X46 GEN2 7.4
                  2014 X30 GEN2 5.7
                  2006 VRS200 SS 5.7
                  2013 X30 GEN2 6.2
                  2013 Yamaha 242LS


                  • #10
                    Originally posted by lashburn1 View Post
                    Thanks kinda funny
                    But 100% true!


                    • #11
                      Well, something fixed itself. Now the gas gauge shows 100% full when it should. I followed the "reset" procedures in the manual which didn't seem to work. I ran the gas down a bit lower than usual and then filled up the gas and it just showed 100%. Not sure exactly what caused things to "fix" itself. Works now, so I guess that's good.


                      • #12
                        Same on my '18 Xstar. I activated fuel management, told it the boat was "full" and it didn't help - but after the next fill up It worked.
                        The question is not whether life exists after death, but whether you were alive before death - Osho


                        • #13
                          When I first got my 2003 I assumed there was a reserve like normal.. nope when my gauge hits E... it's dead empty.. I have proof of that unfortunately