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Fuel Gauge Issue #2

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  • Fuel Gauge Issue #2

    OK I will not post another question about the fuel gauge issue I am having if I can get someone to comment on the following...I promise!

    This is the second new gauge (Equus GM type)
    I have installed the correct Equus sending unit in the tank
    I have checked out all of the positive as well as the negative wire runs even the sending unit wire.
    With all of this I still have the problem of the gauge pegging out past full when the switch is turned on.

    Now here is the new input. Yesterday I took the gauge out and took it to the battery where I hooked up the postive to positive and negative to negative and still the gauge pegs out past full. And this is with sending unit disconnected.

    SOOO Go figure huh?
    Maybe I will have to revert to the old "dip stick" process of knowing how much fuel is in the tank.

    Is it possible that I need a resistor of some type between the ignition switch and the positive blade on the gauge?

    Thanks in advance
    Larry E


  • #2
    Re: Fuel Gauge Issue #2

    No -- you don't need a resistor. But are you certain you need a 90 ohm sender for that gauge? Have you actually worked the sender manually to see if it tracks smoothly from 0 - 90 ohms? Seems to me you are busy checking wires when you haven't verified what you actually have for a guage and sender. Just because the box the sender or gauge came in says it's 90 ohms does not mean that's the case. Stuff has been put into incorrect boxes before. The gauge should also have an "L" (light) terminal. Are you positive you are using the correct terminals? How about showing us pictures of the gauge and the sender. Technical data about the Equus Series of gauges and senders is pretty slim and since these are aftermarket automotive parts, quality may be questionable. IF -- and I repeat IF, the positive and negative terminals are correctly connected, and the sender is disconnected, that suggests an internal problem with the gauge.

    Comment



    • #3
      Re: Fuel Gauge Issue #2

      It's also not unheard of for new units to be faulty. Either a bad batch at factory or damaged during transit.
      sigpic
      85 Chevy C10
      89 Cheetah 210ES Cuddy

      Comment



      • #4
        Re: Fuel Gauge Issue #2

        Originally posted by Silvertip View Post
        No -- you don't need a resistor. But are you certain you need a 90 ohm sender for that gauge? Have you actually worked the sender manually to see if it tracks smoothly from 0 - 90 ohms? Seems to me you are busy checking wires when you haven't verified what you actually have for a guage and sender. Just because the box the sender or gauge came in says it's 90 ohms does not mean that's the case. Stuff has been put into incorrect boxes before. The gauge should also have an "L" (light) terminal. Are you positive you are using the correct terminals? How about showing us pictures of the gauge and the sender. Technical data about the Equus Series of gauges and senders is pretty slim and since these are aftermarket automotive parts, quality may be questionable. IF -- and I repeat IF, the positive and negative terminals are correctly connected, and the sender is disconnected, that suggests an internal problem with the gauge.
        Sending unit is the one that the gauge is matched to. Both are supposed to be 0-90 ohms. I have not taken the sending unit out to test it specifically but will do that. However again the most mystifying part of this is that the same things happens with the sending unit unplugged.

        Larry E

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        • #5
          Re: Fuel Gauge Issue #2

          As Cheetah just mentioned, You would not be the first to get a couple of bad "somethings" due to a bad batch of product or product that is not packaged well and damaged in shipment. In your case, a bad (shoerted) sender has the same effect as jumping the send terminal on the gauge to ground which pegs the meter. If you noticed in the gauge test procedure you were told to "momentarily" jump the send terminal to ground. A shorted sender PERMANENTLY rather than MOMENTARILY shorts the termnals so perhaps the sender is destroying something inside the gauge. Again -"verify" what you have.

          Comment



          • #6
            Re: Fuel Gauge Issue #2

            If you hooked the guage up to the batt positive to positive and ground to ground the guage is going to peg out. the wire fom the sending unit should act as your ground for the guage. The guage then displays the resistance through the sender as the fuel level reading. Show us a pic of what you are working with. How many connections on the guage? Maybe you are hooking the sending unit directly to ground versus the sender post. The more info you give us the better we can help and pics speak a thousand words.
            http://forums.iboats.com/showthread.php?t=400682

            Comment



            • #7
              Re: Fuel Gauge Issue #2

              I'm not sure about your wiring. The sender is a resistor, two wires should be attached to the sender: one pink or purple wire attached to the center contact of the sender, and a black ground from a sender attachment screw to the vessel common ground (not to the gauge, just the same ground circuit although it could). The gauge should have a positive and negative attachment (possibly labeled 'I' for ignition, and 'G' for common ground. The purple/pink wire from the sending unit attached to a terminal labeled something like 'S' or SEND, and maybe a blue wire to an 'L' terminal for a gauge light. The 'switch' could be in either circuit, but probably the 'I' side if you only have one tank. It'll likely be in the purple/pink circuit for multiple tanks (like a Grady). I'm not familiar with Equus, but resister gauges have to pretty much be wired this way. The link is for a Teleflex gauge, but yours should be pretty much the same installation and test. Yours indicates it's either shorted or wired incorrectly ... www.catalina27.org/images/teleflexMF.pdf

              Comment



              • #8
                Re: Fuel Gauge Issue #2

                Originally posted by Allbutwet View Post
                If you hooked the guage up to the batt positive to positive and ground to ground the guage is going to peg out. the wire fom the sending unit should act as your ground for the guage. The guage then displays the resistance through the sender as the fuel level reading. Show us a pic of what you are working with. How many connections on the guage? Maybe you are hooking the sending unit directly to ground versus the sender post. The more info you give us the better we can help and pics speak a thousand words.
                Absolutely untrue. The gauge has POS and NEG terminals that will NOT cause the gauge to peg whether or not the sender is connected. The "S" terminal will see 0 - 90 ohms with zero being equivalent of a short. That zero ohms pegs the meter and 90 ohms lets it sit at empty. An open circuit (sender disconnected) represent infinity so the gauge would also sit at empty.

                Comment



                • #9
                  Re: Fuel Gauge Issue #2

                  Originally posted by Silvertip View Post
                  Absolutely untrue. The gauge has POS and NEG terminals that will NOT cause the gauge to peg whether or not the sender is connected. The "S" terminal will see 0 - 90 ohms with zero being equivalent of a short. That zero ohms pegs the meter and 90 ohms lets it sit at empty. An open circuit (sender disconnected) represent infinity so the gauge would also sit at empty.
                  Thanks everyone. I found an open circuit in the new sending unit. Installed a second new unit and it works...
                  Larry E

                  Comment



                  • #10
                    Re: Fuel Gauge Issue #2

                    Originally posted by Larry E View Post
                    Thanks everyone. I found an open circuit in the new sending unit. Installed a second new unit and it works...
                    Larry E
                    Strange -- because an open circuit is infinite resistance which has the same effect as having 90 ohms in the "S" circuit. The gauge should have read Empty -- not Full if that were true.

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                    • #11
                      Re: Fuel Gauge Issue #2

                      Originally posted by Silvertip View Post
                      Strange -- because an open circuit is infinite resistance which has the same effect as having 90 ohms in the "S" circuit. The gauge should have read Empty -- not Full if that were true.
                      I probably used the wrong terminalogy but I dont care it is working. When tested it showed NO resistance (no ohms I guess) so I exchanged if for a new one and it works. Swabbing the deck and getting ready to lay carpet as we speak.
                      Larry E

                      Comment



                      • #12
                        Re: Fuel Gauge Issue #2

                        Originally posted by Larry E View Post
                        I probably used the wrong terminalogy but I dont care it is working. When tested it showed NO resistance (no ohms I guess) so I exchanged if for a new one and it works. Swabbing the deck and getting ready to lay carpet as we speak.
                        Larry E
                        That means it had a dead short, not an open circuit. But it's quite understandable to confuse these two concepts when you get 0 on the meter, so it's all good!
                        Bob
                        Orange County, NY
                        '88 Bayliner 1700 Capri Bowrider, 85 HP Force O/B, "Sea Weasel"
                        Want a vessel safety check? Click here. Want to join the Coast Guard Auxiliary? Click here.
                        Disclaimer: Although I am a member of the USCG Auxiliary, the opinions and advice in my replies are my own and do not necessarily reflect CG or CG Auxiliary policy or regulations unless so specified.

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