OK. Having got through the access plate in the trunk of the car (It is back by the back of the seat, under the carpet) I have checked the pump on top pf the fuel tank. It bobs up and down a little to the touch and there is a little metal ring with a tightening screw which has apparently slipped off. From all indications, it is intact and could be put back on, or another metal ring and screw thing could be findable... I am just wondering if I should drain the tank before mesing with it. The fuel filler hose and tube look intact.
David in NJ