leaking under car but what is it ?

if its aluminium its the fuel filter, could have corroded due to road salt or the filter becoming blocked, should be covered by a protective guard replace the filter and if no cover was fitted wrap some plastic protection around it .
Fit the new filter the SAME orientation as the old one,or with the ARROW towards the FRONT of the car, check at the clips for leakage, retest with engine running fuel line is now PRESSURISED

wirecutterman
October 2009