Saw this description in looking up engine wiring harness on parts site:

"Wiring harness to be used in conjunction with fuel level sending units on early models with round pin electrical connections."

What's the wiring harness have to do with the fuel level sending units? My fuel gauge goes up and down when the gas tank is just filled up. After 1/8 of the tank is used, the gauge is 100% normal. Any relationship?

Needs context - wiring harness is a generic term, a harness with wires.

When the float rides at the top ( full tank of fuel ) and you have an intermittent contact on the resistor element, it will cause the problem you're describing.
After you've used up some fuel, the feeler does not contact the defective area anymore, and the gauge will work fine.
Sounds like a new sendingunit is in order.

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2007 C 230 Sport.