I HAVE A S80 03 NON TURBO I LOOKED UNDERNEATH AND DIDN'T SEE ANYTHING
I PULLED UP THE REAR SEAT NOTHING. BUT PASS.SIDE THERE A RUBBER BUSHING I PULLED ON IT AND IT RIPPED UNDERNEATH THAT WAS APUDDLE OF GAS INSIDE THE BUSHING ON TOP OF TANK. I USED AN AIR GUN AND BLEW SOME GAS OFF THE SIDE OF TANK THEN GUNNED IT DOWN A STEEP SHORT GRADE THEN BREAKED HARD THEN REV. UP THEN STOPPED HARD DID THIS TWICE . AT THE BOTTOM OF HILL THERE WAS 2 FOOTBALL SIZE SPOTS OF GAS . ON THE WAY HOME AND PARKED I DIDN'T SMELL ANYTHING ...? IS IT POSIBLE I OVER FILLED THE TANK AND IT PUDDLED ON TOP OR IS THERE MORE TO CHECK. ASKED DEALER AN THEY SAY THATS A SIGN THE PUMPS ON IT'S WAY OUT... IS THERE A OVERFLOW VALVE ON THE TANK? WILL PUT 10GALS IN AND KEEP YOU UPDATED

 

Most likely the nipple on the fuel pump assembly is cracked and leaking.
Or the plastic somewhere is cracked. (Very common parts are on national backorder)