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Need a Fuel totalizer. sending unit for tank dead ... 2004 200hp 2 cycle...

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  • Need a Fuel totalizer. sending unit for tank dead ... 2004 200hp 2 cycle...

    I do not have an access port to get to the sending unit on my inboard tank... capacity 85 gallons
    I saw years ago totalizers that were analog... ie: they had a counter... and would not lose the total fuel used.
    inline... or....

    either way... recommended product? needs to work with the SX200TRC...

  • #2
    here is a Yamaha solution - which measures fuel flow, accumulates fuel consumption (until manually reset),
    and if connected to a Yamaha speedo or a GPS will display economy (mpg / km/L)
    with an optional sensor it can alarm for water-in-the-fuel-filter

    if you are using a modern GPS/chartplotter device, that could be connected for the GPS speed

    however you likely then have an alternative solution, of a NMEA 2000 fuel flow sensor such as the Garmin GFS-10


    • #3
      they make plates that you put in the hole you cut in floor over the sending unit so you can get access to it when needed


      • #4
        pictures of sending unit? wire off sending unit? or vent tube? IMG_0613.jpgIMG_0611.jpg


        • #5
          Hey you found it!
          The upper photo is the bonding wire who's other end is connected to the filler cap.
          Its purpose is to prevent static electricity being created as gasoline is pumped into the tank.
          As such it does not have to be connected to the boats electrical system ground - but it can be, and often is.
          In your case, it is not connected anywhere else so has nothing to do with your fuel level sensor.

          The second picture is of course your fuel level sensor - looks like A WEMA - excellent device.
          Now you have to trace back that black jacketed cable - inside there is a pink wire and a black wire.


          • #6
            Thanks for the confirmation on the sending unit. That wire is so stiff that I thought it was a vent hose.

            fairdeal . YOU ARE FUNNY.... that is under a six inch inspection port... under the console... and that cable runs straight aft... under 14 feet of deck... tracing is a hilarious concept.
            16" to starboard the main harness' etc come up through the wire tray with all wiring running fore and aft.. I have to confirm the pink wire does go down through the hull at that point. (I know it does not exit aft)
            or the end of the WEMA wiring comes around and back up under the console.

            this boat sat with around 72 gallons of fuel in a 85 gallon tank for over 18 months.
            The tank has been COMPLETELY drained and filled with 85 gallons of fresh fuel.

            The gage reads full at all times...

            one. is that WEMA a float type sensor... if so... is there a chance it is mechanically stuck?
            .... that port has been fuel tight for 14 years... i hate to open it if I do not have to (plus... the tank is now completely full.. stuffed full)
            two... I show voltage across the gage to the pink terminal. it is showing a ?"carrier"? voltage of 4.8 volts... not sure if it is a 4/20 ma signal.
            three... Is the black "cap" a seal or a cover... anyway to check the instrument itself?
            four... if i do find the actual WEMA cable... what am i checking for? continuity?


            • #7
              Image of instruments with "dash" open on console markup console.jpg


              • #8

                as ubiquitous as 4-20 ma is in process control, for whatever reason the convention for fuel level sensors is different.
                Typically, the gauge outputs ~5V on that "S" terminal which is supplied to the tank "sender"
                which is a variable resistor connected to ground.

                when the tank is empty, the resistance is ~240 ohms; when it is full 33 ohms.

                The most common problem is a non-existent or sketchy ground for the sender, resulting in "empty" or erratically low readings.

                Conversely, a "dead short" between the "S" terminal and ground gives full scale - "Full" indication.

                I can't say its impossible for your float to be "stuck at the top" - but if it is a WEMA IMO that's unlikely.

                Given the appearance of the back of the gauges/wiring - I would start there to look for a possible "short" to ground


                • #9
                  That is exactly what I wanted to know... look for a short to ground
                  That is exactly the info i needed.. what the full vs empty faults would be...

                  I have been chasing wiring all over this boat. The Yamaha wiring is finally good to go. New fuel pump... new oil pump... tach is reading again. voltage is shown from motor.

                  yes... the picture above does absolutely no justice to the mess under the console. Sea Pro guys... stereo guys... GPS guys... radio guys...

                  I am HOPING... it is in the console.. and i am not "shorted to ground" in the hull...


                  i will get back, and tell you I DID find it... sometime this week


                  • #10
                    Have you verified that the gauge works? You mentioned that it shows Full all the time, so I assume you mean with the ignition off, as well?

                    Test the gauge before you start chasing wires. Turn the ignition ON (no need to start engine) and remove the pink wire from the gauge. The gauge should go to empty. Next, short the sender post to the ground post and it should read full.

                    You can test the ground wire from the gauge by shorting the sender post to a known, good ground - such as on the engine or a grounding block. You should also get Full to show.
                    2000 Yamaha OX66 250HP SX250TXRY 61AX103847T
                    1982 Grady Weekender/Offshore (removed stern drive & modded to be an OB)


                    • #11
                      I have still not resolved this issue.
                      The wiring connection from the boat harness to the WEMA sender is somewhere under the deck.
                      There is no slack.. and I cannot get to the splice. I am assuming the issue is in the under deck wiring.
                      Can I cut the WEMA wiring that is shown in photo? I THINK I can get 18" of wiring... if not at least enough to splice on new wiring right above sender.

                      the sensor is literally right below the instrument cluster inside the console.


                      • #12
                        Originally posted by Junglejim03 View Post
                        Can I cut the WEMA wiring that is shown in photo?
                        Sure. Its a heavy jacket with two wires inside (of course you'll want to do nice water/corrosion proof splices)

                        One has to run to the gauge "S" terminal, the other goes to ground - at the gauge or elsewhere (I like pink to "S", black to ground)

                        Now - you did follow Dennis's excellent advice to disconnect the current "S" lead at the gauge -

                        and confirm that lets the gauge go to "E" ?


                        • #13
                          This is current wiring... shows full on ign... all other gages work
                          . A FULL.JPG


                          • #14
                            Yesterday... as i could reach wiring on console...
                            with this wiring... guage would read correctly...

                            A READS.JPG


                            • #15
                              I feel I must have ground short in hull.