If it is leaking where the hose enters the cap.. SEAL ALL, which is very close to the original DUCO model cement (Current Duco is something else entierly) is resistant to gasoline,, Very resistant to gasoline, It is a miracle sealant.
I one spent a week in a tent, Well it rained and sure enough there were some pin holes drip, dripping on we inside the tent, A bit of Seal All on the end of a finger wiped onto the hole and no leak no more.. Same with a leaking gas tank, It stops the leak IN PROGRESS and its resistant to gasoline.
Worked great both conditions.
