Losing fuel

Hi all,

I was hoping someone might be able to help me with a fuel problem. This has been going on for some time now and I can't seem to figure it out.

Car: Defender 110 CSW 300Tdi (1995)

Problem: fuel leaking from filler cap.

Solutions tried:

• replaced fuel cap twice
• replaced filler neck, breather hose and hose to tank
• replaced injector pump diaphragm

My last resort is going to be to try and fit a different sort of filler cap. Currently I have a vented cap (previous ones tried were also vented) and was wondering if it should be non-vented. Does anyone know how to find whether a vented or non-vented cap should be fitted?

Any suggestions on how to solve this problem will be greatly appreciated.

Thanks very much,
Dan