Those floats have a tendency to fail for a variety of reason, but this crap they call gas in the US, with the corn squeezins in it, seems to eat up the floats. They aren't terribly expensive, about $25.00, and I don't think they're covered under warranty. I think that tends to vary a bit between dealers as the warranty presumably doesn't cover electrical bits. I think I had to pay for one.
Oh, yeah, be careful when tightening these things up. The hex is not attached to the threads and as you keep turning the hex and you think it hasn't bottomed out yet, the threads can rip off the hex and keep going up into the tank, then you gotta leaky tank!
When the oring just starts to squish on the hex and the bottom of the tank, stop turning the wrench!
Bare