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Discussion Starter · #1 ·
I have a 1986 safari 377 that works fine other than the fuel gauge just shows empty. I tested the gauge on its own and it worked fine and with the wires disconnected the sending unit has continuity with resistance. There is power to the gauge and I can’t get the sending unit out of the tank without a lot of work as the screws just spin without unthreading. So unless someone knows a common problem with the fuel gauge system or an easy way to get the screws out I’ll just put a sight glass in an disconnect the fuel gauge
 

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I installed one on a 93 Skandic a couple weeks ago. The resistance of the sending unit was from 12 ohms to around 160 I believe. When you tested the gauge, did you apply 12 volts directly to it? If you do this, the gauge will read full but may never work properly again. When bench testing a gauge, place a resistor with a value between 20 and 100 ohms in series with the gauge. There is also a change that the sending unit in the tank might have a broken float. What resistance are you reading at the sending unit? Does this reading change when you add fuel to the tank? A good way to check the gauge when you have the sled apart is to flip the tank upside down and see if the gauge goes up. You have to get the sled running on a jerry can if you go this route. You may also be able to hook the float arm with a bent coat hanger and save you a bunch of work.

I have encountered this same issue with the screw retainers spinning and not allowing you to remove the screws. In this case, I would just leave it alone if it's not leaking. If you fiddle with them too much, they may not squeeze your gasket any longer and you'll be looking at replacing the tank if you cant get it apart.

If you choose to install a sight glass, two 90 degree tank fittings and a piece of fuel line will make you a good homemade gauge. If you are repairing an existing sight glass, the holes in the tank will likely be too large for the tank fittings. In this case, I have used the fittings from old oil injection tanks which are much larger and will seal the holes up.

I have a couple sleds from this era with electric fuel gauge. Let me know if you need any resistance readings or other info.

Hope this helps, happy wrenching
 

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Discussion Starter · #3 ·
Thank you for the help, I did test the gauge with 12v direct but I also disassembled it to check the internals and it has the heater wire and bi metallic strip and I only tested it for long enough to move the needle to full. As for the ohm readings I didn’t check it full but empty I think it was around 92ohms the sled is at my grandparents right now but I will be up there this weekend and I’ll check the readings. If it is the sending unit do you think it’s worth replacing or should I just add a sight glass. Also I do have a spare tank that never had an electric gauge on it if this one starts leaking but do you have pictures of how the sending unit mounts on the inside like what the screws thread into.
 

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I dont have a tank to get a photo, sorry. The screws go into little retainers molded into the tank. Once they spin out on you, I don't know of any trick to get them off other than trying to shove a small flathead under there to try to hold it. Never had success with this and always did more harm than good when I tried. If you're reading 92 ohms, I think your sending unit is likely ok. When they fail, they usually read either shorted or open. Sounds like the issue is likely in the wiring harness or one of the plugs. If you check this over and still can't get a proper reading, I would install a sight glass and go riding.
 
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