Former owner foul-ups.
I'll admit to this one, my error.
I had a different Valiant that wasn't in use and I had it parked on my driveway backed in. Well the driveway had a slope and when it rained the trunk would fill up with water as there was no trunk seal. Smart me I take a drill and went all the way forward to where the differential was and drilled a couple holes, figured I was well ahead of the gas tank, a little later I realized I drained the trunk right into the tank.
Alan