So there's this little tube in the boot which I am pretty sure connects to the petrol tanks and I am guessing prevents excess pressure. Problem is, the back of my car smells like a petrol station... is there a fix for this?

 

DONT LIGHT A MATCH

Not knowing your model etc, there are numerous hoses that connect the 2 tanks to the single supply to the engine, and a couple of vent hoses as well.

Stop the flow the best way you can, for safety obviously, and then systematically trace each hose until the culprit/s is found.

Unfortunately good old "old age" is now creeping into these hoses by now.

 

Really need to dig deeper. The tanks are notorious for leaking at the seams and rusting through in general. You've got all kinds of culprits for this one.

 

If you have old fuel hoses in the trunk (fuel pump is rearward of the spare tire), they can seep and contribute to the smell. Take out the spare and carefully inspect. It is recommended to replace all the old hoses from the tank, to the pump, and from the pump forward to the filter, and from filter to the steel fuel line that goes forward out the trunk and under the car. Use "fuel injection hose", it has SAE J30R9 rating for minimal seepage tolerance, high pressure, and uses a special lining that is much longer lasting than regular hose.

Another possibility: http://www.jag-lovers.org/xjlovers/x...lcondenser.htm
http://www.jag-lovers.org/xjlovers/xjfaq/fuelsmell.htm
http://www.jag-lovers.org/xjlovers/xjfaq/fuelhose.htm