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  • #31
    Originally posted by blue62tbird View Post
    well the wiring to the gauge is good, I have completed the circuit, the gauge moved.
    Moved to where? Did it stay at 1/4 or go higher?

    John
    John Pizzi - Squarebirds Administrator

    Thunderbird Registry #36223
    jopizz@verizon.net 856-779-9695

    http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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    • #32
      Originally posted by jopizz View Post
      Moved to where? Did it stay at 1/4 or go higher?

      John
      When I pulled the wire from the Gauge and I just grounded that wire only, the gauge went to 3/4 and the test light I was using as a ground wire (I figured it was just a wire passing through a light more or less) was flashing, as if the connection was good from the tester to the gauge and back to test light, I thought.
      My temp gauge works so we know the CRV or CVR thingy is good up there under the dash.
      Tim
      1962 Conv Tbird
      1993 Miata LE
      1994 Miata

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      • #33
        I wasn't aware you were just rehashing what you did previously. When you get around to replacing the wire tomorrow or whenever as I suggested let me know the results. If it's just a bad wire from the harness to the sender that's easier and cheaper to fix than the sender.

        John
        John Pizzi - Squarebirds Administrator

        Thunderbird Registry #36223
        jopizz@verizon.net 856-779-9695

        http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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        • #34
          did you think I have been out working on the car during this conversation?
          Tim
          1962 Conv Tbird
          1993 Miata LE
          1994 Miata

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          • #35
            Originally posted by blue62tbird View Post
            did you think I have been out working on the car during this conversation?
            In this era of smartphones anything's possible. LOL

            John
            John Pizzi - Squarebirds Administrator

            Thunderbird Registry #36223
            jopizz@verizon.net 856-779-9695

            http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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            • #36
              I was not. Sorry.
              Tim
              1962 Conv Tbird
              1993 Miata LE
              1994 Miata

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              • #37
                Remove the fuel tank sending unit. No need to replace wires yet.
                Once you get the float assembly out, the whole picture will become clear. It is a variable resistor that should measure ten-ohms when the tank is full and 100-ohms when empty.

                Using a test light in series with ground is good. It proves two things; how consistent and steady the flashing occurs and the simple fact that your wiring has a complete path from the dash to the tank.

                Mechanical CVRs work like your turn signal unit but they are on at all times your key is on. They should output a STEADY 12-volt pulse, 50% on and 50% off. This averages the current to a 6-volt system. When mechanical CVRs get old, the flashing gets erratic because the contacts get pitted and burned. Old CVRs can also stick ON (all the time) or burn open. - Dave
                Last edited by simplyconnected; July 10th, 2018, 07:08 AM.
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                • #38
                  Originally posted by simplyconnected View Post

                  Using a test light in series with ground is good. It proves two things; how consistent and steady the flashing occurs and the simple fact that your wiring has a complete path from the dash to the tank.

                  (all the time) or burn open. - Dave
                  When I did what you said above I did get a steady consistent flash that was not erratic.
                  Tim
                  1962 Conv Tbird
                  1993 Miata LE
                  1994 Miata

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                  • #39
                    If it is the sending unit, I am seeing stuff on Ebay from 40 bucks and up. Dorman, Spectra to name a few, what would be a good brand to go with?
                    Tim
                    1962 Conv Tbird
                    1993 Miata LE
                    1994 Miata

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                    • #40
                      Originally posted by blue62tbird View Post
                      If it is the sending unit, I am seeing stuff on Ebay from 40 bucks and up. Dorman, Spectra to name a few, what would be a good brand to go with?
                      Spectra makes the new fuel tanks so I would go with their sender.

                      John
                      John Pizzi - Squarebirds Administrator

                      Thunderbird Registry #36223
                      jopizz@verizon.net 856-779-9695

                      http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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                      • #41
                        As I explained last night, where my wire goes into the take there is a black rubbery substance or some soft substance, I assume I need to pull that out to get to the top of the sending unit which will not hurt anything, just expose the wire connection to the sending unit. Has anyone seen this before, will I need to put the same thing back in when I put another sending unit (I am putting my money on that being my issue when I get home and test the wires with a new wire).
                        Tim
                        1962 Conv Tbird
                        1993 Miata LE
                        1994 Miata

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                        • #42
                          That was just a sealer to prevent water from getting into the unit. Usually it's soft enough where you can reuse it. If not rope caulk or something similar will work just fine.

                          John
                          John Pizzi - Squarebirds Administrator

                          Thunderbird Registry #36223
                          jopizz@verizon.net 856-779-9695

                          http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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                          • #43
                            I disconnected the wire from gauge/harness from the wire going into the tank. Put a wire between them, same result, stays at 1\4 level.
                            I plugged the wires back up and grounded at the place where the wire goes into the tank (I removed some of the black goo to get a good clean shiny metal surface) and grounded to a good place in truck, several places to confirm same results, every time the gauge pegged out to full.
                            I am thinking bad sending unit.
                            Tim
                            1962 Conv Tbird
                            1993 Miata LE
                            1994 Miata

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                            • #44
                              just for grins, the harness from the guage that comes into the trunk on the drivers side, I giggled it, moved it around, so see if maybe a short was there, nothing changed, so I guess wires are good? I looked at them closely, it all looks nice and clean, I pulled some of the orig factory covering off of them and all seemed in great shape. Nothing pinched or the like that would make you think could be an issue.
                              Last edited by YellowRose; July 10th, 2018, 05:26 PM. Reason: Modified wording...
                              Tim
                              1962 Conv Tbird
                              1993 Miata LE
                              1994 Miata

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                              • #45
                                Originally posted by blue62tbird View Post
                                I disconnected the wire from gauge/harness from the wire going into the tank. Put a wire between them, same result, stays at 1\4 level.
                                I plugged the wires back up and grounded at the place where the wire goes into the tank (I removed some of the black goo to get a good clean shiny metal surface) and grounded to a good place in truck, several places to confirm same results, every time the gauge pegged out to full.
                                I am thinking bad sending unit.
                                It sounds like you've done everything right to prove that the sender is the problem. Before you buy a new one I would remove the old sender and check the float. If it's loaded with gas you may not need a whole new sender, just a new float.

                                John
                                John Pizzi - Squarebirds Administrator

                                Thunderbird Registry #36223
                                jopizz@verizon.net 856-779-9695

                                http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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