Hi. I am driving a BMW X5 and have a problem after filling up the tank I can smell petrol out side when the car is parked.

There is no visible leak and the problem goes away when the tank is half empty.

Can anyone provide a possible reason why this is hapening and offer a solution.

Thanks.
Peter

What year? how many miles? My first guess would be the fuel pump/sender retaining rings are loose or leaking and allowing a small amount of fuel to slosh out into the cavity that they rest in. Then when this evaporates, you stop smelling it.

My X5 is 2003 4.4 litre E53/M62. Done 90,000 kms.

I also suspect that the gasket on the fuel pump/sender unit may be leaking.
Someone suggested the tank could have a crack in it. Ever heard of this on a plastic moulded tank?

Probably more likely that the seal is just failing. But no, I haven't heard of the tank cracking without some sort of outside influence.

We just replaced the fuel sending unit on a Ti because of a small (really tiny) hole in the top of the part. It looked like it had been that way for years. We filled up the tank and made sure we had the smell. We pulled the access cover and found it...