I'd leave it running whilst on ramps, then maybe if there is any leak you'll see the fuel dripping.
I just did me other halfs astra, the leak was so thin, but was on feed side of rail, amazing how much a tiny amount of petrol smells, hers was a leak in a 15 year old fuel pipe, it was dripping on the exhaust as well, luckily away from any sparks, only saw that when on ramps, tip don't let petrol drip in your eyes, yes it bloody stings!!
tabetha