Are you ******* serious?
You're using rubber parts, in fuel, from the store that is notorious for smelling like degrading rubber, and you can't figure this out?
Stop buying **** parts and you'll stop having problems with **** parts.
Fyi, "petroleum resistant" means they won't melt just from being downwind of a gas station. They're NOT fuel - rated (hint: nothing at harbour freight really is). They will still break down almost immediately in air, water, sunlight, uv light, earth's gravity, and most certainly gasoline. Ethanol probably SLOWS the break down of that garbage.
Get your auto parts from an auto parts store and stop giving your money to a bunch of knockoff hacks in China.