funny sound from petrol tank???

[fordy]

Hi, I looked at a Chimaera this weekend - it all looked OK apart from it had a sound like 'running water' from the top right hand corner of the petrol tank. It sounds like the fuel excess fuel going back into the tank and hitting the tank wall - but looking at the fuel system diagram, it shows the return fuel comes back into the top left (near the fuel filler) - Has anyone else noticed a sound like this??? Also - what would you say is an acceptable amount of rust on the chassis ??- this seemed to have a fair bit around the body mounting points thanks for any advice Chris