What year is the car?
Check for rust on the tank and if any of it has gone through.
Check the filler pipe is connected to the tank still and any jubilee clips on it are tight.
Also check the filler neck pipe for any splits, cracks or holes.
Check the tank for damage if you have driven over any branches or angular curbs.
Depending on age... check hoses coming out the tank to fuel pump/filter for any signs of wear, splits or looseness.
Si V, October 2010