Hi hopefully someone can help me, I have a 2010 Roadster, the fuel gauge isn't playing nicely, ignition on gauge shows full tank, gauge only moves to 3/4 full after 300 km, is the problem the fuel sender? if so whats the solution, replace the sender?If so how do I find it?

thanks Grissly

Volvo XC60 x2
Volvo C30
2010 Roadster
2001 Triumph Thunderbird