This is why a fuel sender dies. (with pic)

Discussion in 'Fuel and Air Systems' started by TrailBeast, Jul 21, 2018.

  1. TrailBeast

    TrailBeast Slightly Twisted Member

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    Outside of electrical supply and ground issue's, this is the main cause of fuel sending unit failures.
    You can see the wire wrapped around an insulated curved piece where a contact connected to the float arm slides causing the resistance to the gauge to vary showing different fuel levels.

    Note the broken wire by the red arrow.
    This causes the gauge to only work if the contact is above the break in the wire because everything below the break is disconnected from the rest of the wire and therefor will not make a reading on the gauge.

    This break in the wire caused my gauge to only read the fuel level if the level was above 1/2 tank.
    Otherwise the gauge showed empty.

    Just thought some might be interested if they have never seen this before.

    sender.JPG
     
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    • pishta

      pishta I know I'm right....

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      I had the contact slider pull away, just a little bend and it was back on track. I also saw one whos contact was rotted off, probably empty for decades with moisture ingress. Could you solder than one back together?
       
    • krazykuda

      krazykuda FABO Gold Member FABO Gold Member Technical Editor

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      Can that be soldered or repaired in any way, or replaced completely with a new unit???
       
    • joshcook81

      joshcook81 Well-Known Member

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      Hmm... my full gauge does exactly what your saying. It will show full tank of gas when I fill up and at half a tank it shows empty. Now I know Why. Thanks TrailBeast
       
    • TrailBeast

      TrailBeast Slightly Twisted Member

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      If the wire fails I don't feel comfortable soldering them.
      For what one costs it's worth changing out for a new one.

      Here's how I go about putting a new one in.
      I disconnect the old sender and hook the new one up to the wire and ground the hanging sender.
      Then I check the gauge to make sure that when the sender float is all the way down, that the gauge is also.
      Then I pull the old one and lightly install the new one with only the wire connected up.
      I put a gallon of gas back in the tank and pull the sender to bend the float arm and test again until the gauge just barely moves off empty.
      Now I put the sender back for the last time with the feed and return lines all hooked back up.

      This way I know when the gauge hits empty I have about one gallon left.
       
      Last edited: Jul 21, 2018
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      • jos51700

        jos51700 Well-Known Member

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        So how come so many new ones are absolute shit?
         
      • TrailBeast

        TrailBeast Slightly Twisted Member

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        Because compared to the OE senders they are cheap shit.
        I get mine through Summit Racing (like that matters) but the 1-2 day delivery time is why from them.
        I need a new one about every 6-7 years of daily driving as the pickup contact wears through the wire wrapping.

        It does extend their life if you vary how much gas you usually put in it at a time.
        If it's always in the upper part of the gauge it will wear out up there first.
        If you always put 10 bucks it, it will wear out that area of the contact wire first.
        It seems filling up and running it down most of the way before filling up again makes them last longer, due to spending less time in one range of the gauge.
         
      • TrailBeast

        TrailBeast Slightly Twisted Member

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        Yea, I have fixed a few but once the contact wire starts going I don't bother.
        I have seen some with the contact arm completely worn through before the wire wore through.
        They used to have a copper button on the arm, but now that part of the arm is copper and a lot thinner with no button.

        Won't be long now before everything we buy only lasts 90 days, and that only if it works at all when we put in on.:D
         
      • jos51700

        jos51700 Well-Known Member

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        So what needs to be redone to have oe style quality? Carbon button? Better resistance wire? Can't be that hard. I'd rebuild an oe I'd that's what it took and was possible
         
      • 72bluNblu

        72bluNblu FABO Gold Member FABO Gold Member

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        Aren’t the OE ones wrapped differently than the reproductions? Something about the resistance varying over the throw of the pickup to account for the non-linear way the volume of the tank drops because of the spare tire cut out?

        Also pretty sure there’s a guy back east that rebuilds the OE senders, they’d have to be better quality than the reproductions. I’ve seen his contact info on here somewhere.

        Although that said the one in my Duster has been working fine. It’s not accurate to the amount of fuel, ie, 1/2 a tank doesn’t mean 1/2 a tank. But it’s consistent, and I drive it enough to know how what the gauge shows corresponds to what’s left in the tank. Plus it’s a 3/8” sender, although I’m sure there’s some way to pair the OE guts with a larger tube...
         
      • Tooljunkie

        Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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        I just replaced a fuel sender in an 06 malibu.
        The brush wore out. At 130,000 kilometers.
        All it is -a miniscule little stainless fork that runs across a circuit board. $100 for a 2 cent part.
         
      • TrailBeast

        TrailBeast Slightly Twisted Member

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        Looks like mostly the point where the button (used to be copper or maybe nickle) and probably the quality of the resistance wire wrap.
        The button would probably be pretty easy to add, and bending the metal contact back a little as to not add more pressure on the resistance wire.
        The BIG problem would be finding that same resistance wire to re wrap with.
        I imagine it has to be measured by amount of resistance drop per inch or something like that.
        It must be out there somewhere or repair places couldn't repair them.




        Exactly, and the insulator seems to have small notches in it's edges where the wire wraps just for that difference.

        I have an aftermarket gauge, but it's ohm range is the same as OE Mopar and some Fords use, so I can still order the OE Mopar sender and they are real close in the reading.
        What I care about most is knowing exactly when empty is, so being a little off in the middle of the gauge (if it is) doesn't bother me.
        I have a 13 gallon tank and if I put 6 gallons of gas in it the gauge shows pretty much exactly 1/2 tank.
        If I fill it all the way it shows exactly on the full mark.
        That's close enough for me.
         
      • KitCarlson

        KitCarlson Well-Known Member

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        People with patience, buy a spool of the correct nichrome wire and rewind them. :)
         
      • Daves69

        Daves69 Well-Known Member

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        Lol, these are bad enough! I can't imagine doing that sender.....
        upload_2018-8-1_19-32-44.png
         
      • KitCarlson

        KitCarlson Well-Known Member

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        I do crazy stuff. Helping the wife at the moment, by restoring a 1936 Singer featherweight case handle. Doing leather work. The sewing is done with two treads, just like interlocking square waves. :) Using pins and original stitch holes.
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