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My fuel sender is kind of accurate from 1/2 to full tank. It stops sending info to the speedo after about 1/2 tank and this is kind of annoying Out of the tank the float seems to move freely. Is there any trick to get it to send it's rough estimate below 1/2 tank? Bending/cleaning/anything?

Tips on how to get this working would be very welcome.
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Molto Verboso
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They are a variable resistor. Pretty random range that seems unique to Vespas at 0 to 350 ohms (from memory). Chuck a multimeter over it and see what readings you are getting.

Guessing if it isn't reading properly then replace.
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parallelogramerist
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I'd try sanding those wire wraps on the sender with some 400-500 grit sandpaper.
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Depends how it is responding. If you get good readings then it could be the gauge itself. If it is reading ok to half then stopping there must be a short/break) in the wires because not increasing/decreasing resistance beyond that point (can't recall if it goes up or down).

Is it just sticking at half on the gauge even when below?
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It sticks to half when the tank goes below. It works as good as it can before the tank is half empty. So that leads me to think that the error is mechanical rather than electrical.
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Molto Verboso
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psgnw wrote:
It sticks to half when the tank goes below. It works as good as it can before the tank is half empty. So that leads me to think that the error is mechanical rather than electrical.
Could be either. Works like this - current goes through sender which is a variable resistor. That then goes to the gauge which has a small thermoplastic coil - it 'heats' opening the coil which moves the dial.

If you can put a multimeter across the sender and move the float you will quickly work out where the problem is - if the ohms are reading ok top to bottom then it is either the float is getting stuck in the tank, or the gauge isn't responding properly. If the sender ohms also stick at halfway, then it maybe a contact with float problem and cleaning that up might help - but I don't actually know enough detail about the sender/float to guess. Post results and happy to try help.
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Also - I assume the dial does go to the bottom when the Vespa is off? Which would rule out a mechanical problem with the gauge.
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Thanks for the replies When turned off it goes to empty. I'll get my multimeter out on the weekend and see what I can figure out.

Funny thing is that earlier it was stuck on empty. Pulled it out before summer and cleaned it up and it started working from full to half.
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