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Fuel gauge sending unit repair with pics

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    Fuel gauge sending unit repair with pics

    Tonight I was sick of the usual GS forum bullsheet, so I decided to rework my fuel gauge sending unit. I've gotten pretty good at working these things out, and I'm sure lots of you guys have malfunctioning fuel gauge sending units. The most common problem I have seen is the float arm pickup not hitting the coil properly or at all. Hopefully I'll explain the process well enough for you.

    This is the sending unit location (duh) :? :

    It's the unit on the inside of the tank, with two wires and the drain hose coming from it. There isn't a need to drain all the gas out of the tank, I drained until I hit reserve and left it at that level. Then keep the cap on, and lay it on it's side. My Workmate bench is perfect for this as it has two big jaws that open up and can hold the tank nice. Use a blanket so you don't scratch the paint.


    Take the four phillips head screws off to remove the drain unit. I'm missing one!

    This is the backer plate to the sending unit itslef:

    Make note of the position of the backer plate in relation to the tank. You need it to go in exactly in this position. Mine has a black dot telling me which way is down. Remove the 5 8mm bolts to free the sending unit.

    Here is a look at the gasket:

    Here is the tricky part. You need to remove the sending unit from the tank without damaging the gasket. The float arm is about 10" long, and the electrics are in a housing that barely fits through. Try not to force it much, and fiddle it around until you can pull it through.

    Hopefully you have gotten the unit out without damaging the gasket, and you have it on the bench like this:


    Next, you need to remove the cover to the guts of the sending unit. This picture shows the small tabs you need to bend up with a small screwdriver to take the cover off:


    Here is a the unit with the cover off:


    Ok, now see this amazing picture I made up for the rest of the direction:


    After you get the guts working well, you can test it with a multi meter. I don't know what the figures should be, but it can tell you if the voltage is changing when you move the float arm, and that's usually the key to success. I also had to bend the actual float arm to get it to read the right amount of fuel, kinda like rasing the level in the toilet bowl by bending the float arm in there.

    The real trick is getting this sensitive piece of equipment back into the tank. Ever do those tavern puzzles? It's kinda like that. Take your time, move it around a bunch and see what works. Sometimes the float arm gets pushed over the limiting tabs during installation. You can use a clean screwdriver to push it back over if that happens.

    Hope this helps some folks, It worked for me three times so far.

    C-YA.
    Currently bikeless
    '81 GS 1100EX - "Peace, by superior fire power."
    '06 FZ1000 - "What we are dealing with here, is a COMPLETE lack of respect for the law."

    I ride, therefore I am.... constantly buying new tires.

    "Tell me what kind of an accident you are going to have, and I will tell you which helmet to wear." - Harry Hurt

    #2
    8O


    dood, you were bored weren't you? :?


    Thx man

    I need that. Mine went south years ago. The float is loose in the tank and can float from side to side. The one on my current GS works.

    Comment


      #3
      dood, you were bored weren't you?
      Not really, just sick of the Buffalo Breath and dynorider garbage!

      It needed to be done, it's the only thing that didn't work factory fresh. Perfect now!
      Currently bikeless
      '81 GS 1100EX - "Peace, by superior fire power."
      '06 FZ1000 - "What we are dealing with here, is a COMPLETE lack of respect for the law."

      I ride, therefore I am.... constantly buying new tires.

      "Tell me what kind of an accident you are going to have, and I will tell you which helmet to wear." - Harry Hurt

      Comment


        #4
        Jethro - I've got to hand it to you, that's what this site is all about and you did an excellent job on the procedure ... 8)

        Comment


          #5
          Thanks Jethro....I was always curious about how this system
          was housed.....and your right, sure beats the bullsheet.

          Comment


            #6
            Great

            Your information and pictures are absolutely EXCELLENT. Great job!
            1980 GS1100E....Number 15!

            Comment


              #7
              Great article Jethro

              Frank should put it in the Garage

              Comment


                #8
                Additional Useful info.....

                I did mine and wanted to add some info for those who may have a set up similar to mine. I have an 82 GS850GL. Since I have a new tank I wanted to check mine since I had the float out anyway. What I noticed on my float that I didn't see on yours (could just be the angle of the photo too)
                I have a set screw on the movable wiper arm that goes up and down. The system works on resistance, the more the resistance the lower the reading on the fuel gage. Lower the resistance and the needle moves towards full, when the wiper arm moves it changes the resistance output. My needle never went all the way to full so I hooked up the wiring harness while holding the float assembly and turned the ignition switch to on. I moved the wiper blade down until I was satisfied with where the needle stopped on the full mark then tightened the screw... Make note that when you loosen that set screw the float arm becomes disengaged from the wiper arm so make sure the float is in the up or down position depending on which setting you are trying to adjust before you tighten the set screw. I believe the set screw is there for this adjustment purpose so you don't have to bend the metal tabs to change the float hight, unless you don't have a set screw. Also some corrosion can build up on the resistance pad that the wiper arm rides on and can alter the reading lower then normal, remember the higher the resistance the closer the needle moves to empty. Disconnect the wires and turn on the ignition switch, the needle will move to empty. Also on the back side of the wiper arm can get corroded changing the resistance. I used an emery board to clean the contacts as best as I could. Take note changing the position on that wiper arm the slightest amount can make drastic changes on the needle. I first tried using my Fluke meter to read the resistance output but the fluke is so sensitive I gave up and used my trusty old Simpson Meter, for those old timers a simpson is an analog meter and in my opinion a much better bench meter then a fluke. I was able to get resistance readings in the teens on the lowest setting, matched that to the bike hooked up and it was a match.
                you can either set the wiper arm until you get the lowest resistance reading possible, this will in fact set the needle as close to full as possible, and on the other end it will make it to empty and slightly past, there is more room on the empty side of the adjustment then there is on the full side.
                Those who are not satisfied with the needle placement on full you might want to give this a try, also make sure that the wiper arm stays in fulll contact throughout the entire sweep motion, should it break away at any time between empty and full the needle will drop to empty even though you may have a full tank. Or those whos needles drop to empty at one point only to rise again later on this is what your problem is, the wiper arm is not making contact somewhere along the resistance pad...
                The info and pics you provided are better then factory manual repair books, well done, thank you for those who don't take the opportunity the thank you for doing all that work...
                Thanks Bill

                Comment


                  #9
                  Additional Useful info.....

                  I did mine and wanted to add some info for those who may have a set up similar to mine. I have an 82 GS850GL. Since I have a new tank I wanted to check mine since I had the float out anyway. What I noticed on my float that I didn't see on yours (could just be the angle of the photo too)
                  I have a set screw on the movable wiper arm that goes up and down. The system works on resistance, the more the resistance the lower the reading on the fuel gage. Lower the resistance and the needle moves towards full, when the wiper arm moves it changes the resistance output. My needle never went all the way to full so I hooked up the wiring harness while holding the float assembly and turned the ignition switch to on. I moved the wiper blade down until I was satisfied with where the needle stopped on the full mark then tightened the screw... Make note that when you loosen that set screw the float arm becomes disengaged from the wiper arm so make sure the float is in the up or down position depending on which setting you are trying to adjust before you tighten the set screw. I believe the set screw is there for this adjustment purpose so you don't have to bend the metal tabs to change the float hight, unless you don't have a set screw. Also some corrosion can build up on the resistance pad that the wiper arm rides on and can alter the reading lower then normal, remember the higher the resistance the closer the needle moves to empty. Disconnect the wires and turn on the ignition switch, the needle will move to empty. Also on the back side of the wiper arm can get corroded changing the resistance. I used an emery board to clean the contacts as best as I could. Take note changing the position on that wiper arm the slightest amount can make drastic changes on the needle. I first tried using my Fluke meter to read the resistance output but the fluke is so sensitive I gave up and used my trusty old Simpson Meter, for those old timers a simpson is an analog meter and in my opinion a much better bench meter then a fluke. I was able to get resistance readings in the teens on the lowest setting, matched that to the bike hooked up and it was a match.
                  you can either set the wiper arm until you get the lowest resistance reading possible, this will in fact set the needle as close to full as possible, and on the other end it will make it to empty and slightly past, there is more room on the empty side of the adjustment then there is on the full side.
                  Those who are not satisfied with the needle placement on full you might want to give this a try, also make sure that the wiper arm stays in fulll contact throughout the entire sweep motion, should it break away at any time between empty and full the needle will drop to empty even though you may have a full tank. Or those whos needles drop to empty at one point only to rise again later on this is what your problem is, the wiper arm is not making contact somewhere along the resistance pad...
                  The info and pics you provided are better then factory manual repair books, well done, thank you for those who don't take the opportunity to thank you for doing all that work...
                  Thanks Bill

                  Comment


                    #10
                    Re: Fuel gauge sending unit repair with pics

                    Originally posted by Jethro
                    Hope this helps some folks, It worked for me three times so far.

                    C-YA.
                    Uh.....different bikes, I hope. :?
                    Believe in truth. To abandon fact is to abandon freedom.

                    Nature bats last.

                    80 GS850G / 2010 Yamaha Majesty / 81 GS850G

                    Comment


                      #11
                      Great writeup! I need to do this to my 1000. But I can't see any of the pics except the first one :?

                      For my 1000, the replacement gaskets are still available. The sending unit is too, but it's pricey. Fixing the old one sounds better.

                      Debby
                      1979 GS1000N
                      2019 Kaw Z900RS
                      plus a few more

                      Comment


                        #12
                        Gas gauge repair

                        Well thanks to you being fed up I used your write up and did my sender last night. Now it works perfect. Great subject at just the needed time.

                        Comment


                          #13
                          Uh.....different bikes, I hope.
                          Yes, all three different bikes.

                          As a postscript to the article, my 83 was having a strange problem that I didn't specifically note above. At idle the gauge would read correctly, but when I throttled it up it would drop, reading lower until I let off the throttle. I assume what was happening was the vibration was causing the contact arm to break contact with the coil. Making the contact arm hit with more pressure fixed the problem.
                          Currently bikeless
                          '81 GS 1100EX - "Peace, by superior fire power."
                          '06 FZ1000 - "What we are dealing with here, is a COMPLETE lack of respect for the law."

                          I ride, therefore I am.... constantly buying new tires.

                          "Tell me what kind of an accident you are going to have, and I will tell you which helmet to wear." - Harry Hurt

                          Comment


                            #14
                            Jethro I wish I had read this before working on my unit. It would have saved some time. Your last message is interesting. My gauge behaved the same way so I took the unit out once more and tightened up the contact. Problem went away!!!

                            Comment


                              #15
                              I just discovered this post and I have a comment to add that may affect some. When I repaired the sending unit on my GS650E I discovered the sending unit slides on the bushing causing some unreliability issues with the reading. I haven't fixed it yet, but I will add a post when I do. The bushing and arm are somewhat inaccessible on my bike. It still works but is not satisfactory.

                              Just something to watch out for. Considering how they are fastened it is probably a fairly common problem

                              Comment

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