here is the basic problem with pressurized fuel systems. if there is a leak (cracked weld, bad O-ring, etc), the pressurized fuel will spray out of the tank/vessel at high velocity (the smaller the hole, the higher the velocity) causing a mist. the fuel will have also absorbed some CO2 at 15Psi and when it sprays out of the tank the absorbed gas will "foam" the fuel when it hits the normal pressure of the atmosphere. just like you would have with fast decompression in diver's blood, or opening a can of pop or beer (which has less pressure than 15Psi). so, now you have a cloud of misted/vaporized fuel and if it catches on fire, e.g. when it hits a hot header or hot brakes or static will explode in the air, causing concussive injury to people and damage to equipment; meanwhile the leak that is still there will continue to spray fuel, which is now probably being continuously ignited by the remnants of the air burst, until all of the fuel has been expelled or the tank explodes because of the heat causing over pressure in the tank, assuming it didn't burst in the air burst earlier. of course, things are much worse if the pressurized tank bursts first, i.e. when it falls over or gets hit by someone and the pressurized gasoline disperses in larger volume then a small leak. but, even a small fuel air explosion is very impressive...
in general, pooling fuel on the ground from a leak is much harder to ignite.