Spectra fuel sending unit

Fuel and Air Systems

  1. Paul King

    Paul King MrPJK

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    Has anyone had luck with a spectra fuel sending unit .the sending unit i have in the car goes to full then drops like a rock to empty after a few miles on my 66 Dart .Thanks
     
  2. Early a body

    Early a body Well-Known Member

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    Yes,
    They suck. They read completely wrong. I have not been able to find a a/m sending unit to work with the early a's. I Have the original one sent out for repair instead.
     
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    • Paul King

      Paul King MrPJK

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      Thanks ,you just saved me money.im in Canada so i dont know to send one to be repaired
       
    • Early a body

      Early a body Well-Known Member

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      do a google search, i cant remember the name of the last guy I used. He was in the mid west somewhere. Came back really quirk , within a week of me sending it to him. This was about 10 years ago the last time i had to deal with a bad sending unit
       
    • 67Dart273

      67Dart273 FABO Gold Member FABO Gold Member

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      There are two problems with non original senders.
      1...the resistor is originally tapered, not only physically but resistance. That is actually an electronic term. The sender resistor is not "linear" taper
      2..the aftermarket senders (some at least) don't have the proper full movement of the float due to a shorter than original float arm

      However if you get one that is "not terrible off" you can correct the reading with a device called a "metermatch"

      MeterMatch Fuel Gauge Interface Module
       
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      • toolmanmike

        toolmanmike Moderator Staff Member FABO Gold Member

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        There's probably a dozen or more threads here about how bad aftermarket senders are. Just sayin'
         
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        • 4spdragtop

          4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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          Watching,l:popcorn:
           
        • MoparMike1974

          MoparMike1974 FABO Gold Member FABO Gold Member

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          • Dana67Dart

            Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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            Imho the A 100 sender is no better than the other aftermarket.
            Product Review: A100 Fuel Sender For 67 Dart

            Look at the graph at the end of the post, the red diamonds are the resistance the sender wants at a particular level, the graphs of the senders represents the resistance provided by each sender at a particular fuel tank level, the late model oem unit is almost correct the others are too liner.
             
          • Paul King

            Paul King MrPJK

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          • crewchief

            crewchief A & P Mechanic FABO Gold Member

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            Do you still have the OEM unit? If so, get it rebuilt by Instrument Specialties, Inc., N. Kingstown, RI 02852.
            They are the best in the industry, had mine done by them. Very nice work.
             
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            • 1969383S

              1969383S FABO Gold Member FABO Gold Member

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              A few things.

              This was completely functioning in 1988 when the car was put up for 25 years and always seemed very close to 90+% accuracy. It looks bad and meter testing is all over the place and inconsistent.

              Thus being, I was concerned when resto started in 2012 and the tank was a mess!

              I sourced a new tank and Pickup/sender that was Spectra brand. It was not as accurate as I had hoped for on initial resto/re-fire in 2014. Based on the amount of fuel I put in.

              I did update my full gauges with Charger Specialties units a year after life began "again" for the fish in late 2015. Since then my Fuel gauge has been pretty Damn accurate!!

              Never mind the 3/8 line to feed the 800AVS! All the line at resto was increased to 3/8. The 5/16 line may have even been some cause for vapor locking issues from the past!

              Moral of the story is, do not just blame the newer aftermarket design. There may be more contributing factors involved.

              IMG_2932.JPG

              IMG_2933.JPG
               
              Last edited: Sep 22, 2021
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              • Dana67Dart

                Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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                Not sure where you are going here, but tvat sender is easily repaired. The how to here on fabo details the procedure.

                As for aftermarket senders...

                If the sender is not tuned to the guage AND the tank it will never be accurite.

                If your aftermarket sender is tuned to your aftermarket guage it should read fairly accuritely. Only the shape of the tank is the variable and after the first 5 gallons or so the tank is fairly liner.
                 
              • Paul King

                Paul King MrPJK

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                Mine goes from full to empty after a few miles
                 
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                • 4spdragtop

                  4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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                  Hole in float, causing it to sink and registers empty?
                   
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                  • 1969383S

                    1969383S FABO Gold Member FABO Gold Member

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                    Pretty Simple.

                    Everyone bashes the aftermarket sender stuff as not being accurate! They also come up with this list of reasons, or thoughts as to why!

                    I say you need to look a bit Further! Match new with old and ohh! Wire resistance and a tired A-body v-reg fuel gauge + everything to do with these 50+ year old cars must be taken into consideration!

                    I am giving a shout out to Charger Specialties gauges, M&H harnesses and more as they work well with either! One of the smart things I have done, to offset the Dumb!

                    We have all read the Values of resistance oh so many times! yet this simple problem keeps arising for some! It is is more than a check at the sender. It must be the same all the way to the gauge terminal at a minimum.
                     
                    Last edited: Sep 22, 2021
                  • 1969383S

                    1969383S FABO Gold Member FABO Gold Member

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                    This is plausible, However if it does the same thing every start-up cycle then no. Wiring/Sensor/Gauge are all suspect!
                     
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                    • Dana67Dart

                      Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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                      You can disagree all you want but the science is valid. The aftermarket senders with NON aftermarket guages are not compatable.

                      The shape of the tank, the curve of the guage and the curve of the sender all have to match up. If you have a rectangular 18 gallon tank with 9 gallons of gas in it the float will be 1/2 way through its travel.

                      BUT with our tanks with the cutout for the spare, the slope on the bottom of the tank the sender float will not be 1/2 way through its travel with 9 gallions in the tank. That is one reason why a sender that is liner reads in accuritely.

                      Sure the wire from the tank to the guage adds resistance, sure the IVR isnt what it used to be, and the guage is a little worse for wear, but none of that explains the fact that 3 senders in the same car with the same tank and guage and ivr and wire only 1 reads correctly and that one is the OEM unit.
                       
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                      • MoparMike1974

                        MoparMike1974 FABO Gold Member FABO Gold Member

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                        I have the A100 sender in one of my cars and its damn close. Not perfect but good enough. I had a tank on the bench and spent some time adjusting the float lever and the full stops until it read right. I hooked up an oem fuel gauge to it running off a 5v power supply to verify operation.
                        I also run a solid state VR for fuel gauge. No more bouncy needle.
                         
                      • Paul King

                        Paul King MrPJK

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                        I dont have everything you have ,what would be an easy close way to adjust .it dosent need to be perfect
                         
                      • MoparMike1974

                        MoparMike1974 FABO Gold Member FABO Gold Member

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                        You can do it in the vehicle. Mount the sending unit, remove the filler neck so you can see inside.
                         
                      • Paul King

                        Paul King MrPJK

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                        What is it i should see .
                         
                      • MoparMike1974

                        MoparMike1974 FABO Gold Member FABO Gold Member

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                        Make sure the float is going all the way to the bottom of the tank and all the way to the top. Move the float by hand and verify the readings on the gauge at multiple levels.
                         
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                        • Paul King

                          Paul King MrPJK

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                          Thanks
                           
                        • RedFish

                          RedFish Well-Known Member

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                          My aftermarket sender stopped working after some years. Its issue was a hole in the float. When float fills and sinks gauge stays at empty , not come and go. Entire new sender from Rockauto didn't cost much more than a new float and seal would have cost.
                          When my gauge gets down near empty, about 8 gallons fills the tank. The real gas I run is expensive so I'm glad the tank wasn't really empty.
                           
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