C2 Fuel Gauge issue

[napping]

I have an issue with my fuel guage. After a long spell when the C2 was laid up the fuel gauge showed 1 bar, so I filled the petrol tank and now the fuel gauge is showing no bars at all! I suspect there may be an issue with the sender unit. Does anyone have a suggestion on how to test the sender?

[wheeler]

First thing to try is a BSI reset by disconnecting & reconnecting the battery. Failing that you may need to pull the sender out for a look.

[ozvtr]

I have seen black stuff build up on the wiper of the fuel level sender and cause the circuit to fail.
If you have a multimeter you can check the resistance of pins 5 and 6 of the fuel pump module. You should get some sort of reading in ohms. My bet is that it's open circuit.
The wiper contacts can be cleaned but you need to remove the fuel pump module. The retaining ring can be a pain to remove. Also, the blue o-ring gasket under the top will swell and you wont be able to get it back in.
The o-ring absorbs fuel vapors and swells up to form a seal. The o-ring will go back to normal size if left to "air" for a few days. If you cant wait, then you'll need to obtain a new o-ring.

[wheeler]

On that note I should also have mentioned if you need to remove the sender from the tank make sure to run the fuel down as much as possible before removing the ring that holds the sender in. Ideally there should be no more than a quarter of a tank of fuel as plastic fuel tanks are known to sometimes distort if the ring is removed with too much weight in it & you can end up not being able to get the ring back on at all.