Many older American Skiers were equipped with a Perko fuel fill fitting, easily identified as a chromed-zink fitting with a black plastic screw in cap. I have recently come across (2) boats with a "raw fuel" odor from the back of the boat, easily dismissed as fuel overflowing from the separate vent fitting also at the transom. The problem was actually a cracked plastic fill fitting cap. To check, simply remove the cap & try to look through the plastic, both cracks found were at the base of the "key slot" for the opening tool & is hard to see when screwed into the fitting, but easy when removed.
Perko still makes these fittings, I elected to go with an all stainless one.
