Metering Unit Rebuild (Fuel Gauge sensor)

[Dave of Hutto]

Sending unit, metering unit, sensor. What ever you call it it goes in the gas tank and it goes bad with out any available new.
What I did was use a media blaster with 80 grit aluminum oxide. I pulled the cover off and exposed the wound resister and tang. I blasted it gently? 80 lbs of air and just moving over it at a medium rate. I did not want to blow through the wire so I kept it moving. Works like a champ. Mine was orignal to the bike so it was set and works accuratly with the gauge. Even though I used a digital Ohm Meter I could not get a "steady" reading, it was all over the place when I did it manualy. I got zero and I got some higher readings. It acts correctly when floating in gas. Sorry no photo. See my last post in this thread for more detail.

[Whiskerfish]

I have pulled a couple that were full of rust and cleaned them real good and placed them back in service. It is just a crappy old slide resister with a tin box around it.

[Dave of Hutto]

Well alrighty then, I guess I well pull the seat and give it a look. My 76 has 60 ohms when full. it well work right after if is full but any drop in level and it drops to E, not below however. BTW it is suppose to have 0 ohms when full. It camn be measured at the connector located in the side cover. left side top corner. 4 wire connector yellow/w, green /b, green, white /r. the yellow wire to ground well give you the resitor value. half in theory( repeat in theory) should be 30 ohms, 3/4 is 15 ohms, 1/4 tank should be 45 ohms give or take a few.

[Whiskerfish]

I just check a spare 77 I have and it reads 86 ohms empty and 4.5 full. I have no idea if that is correct but it may give you a starting point. This sending unit is in pretty rough shape but the readings were very consistent as I moved it up and down.

[Dave of Hutto]

In my effort to expand the knowledge base I have taken the tank out, bought me a sandblaster, actually it is a media blaster as it won't work with sand. I purchased 70 grit Aluminuim Oxide. I pulled te cover off the sending unit and lightly blasted the rust out of it. I then used a piece of 1/2 in PVC pipe and cleared the screens in the tank and generally knock all the rough stuff out of the tank. To clear the screens, just put the pipe down on top of them and hit it with the media. turns them nice shiny brass color and knocks off the rust scale. I used a rubber line to come in from the side and hit it that way, for good measure I blasted down the fuel lines. All this with the tank out. After dumping the media out ( I dumped it on a table top with a hole to put the media back in the container and reused it several times during this process. I then used some rust removal jelly and sloshed it around for about 10 to 15 minutes then rinsed with water, lots of water. Took a pint of the cheapest alchol I could get . Dump this in and swish it to bond with the water. Dumped it and blow dried with a shop vac. Spray some WD40 it to keep any residual moisture from rusting it up during install. It only takes it a few minutes to get a layer. I also used a soft wire , the same stuff used to tie rebar in concrete forms, to clear the fuel lines. after you get down so far use a pair of pliers to keep pushing it through. Cleared my primary clogged line.