I would start by checking any leaks in your exhaust and fuel filter area, if there is any leaks throughout the exhaust the smell of gasoline or exhaust may come through into the interior.
SOUNDS LIKE A BROKE TIMING BELT
gasoline odor removal from clothes
Because of what it is made from
Gasoline contains benzene,C6H6, which naturally forms in crude oil, and is furthur refined in gasoline used by our cars. It has a characteristic sweet smell. It is also a known carcinogen.
only 2 reasons if here was no smell before changing filter. did you spill gasoline? the smell will go away. is the filter leaking?
no
I could be in the shower and I could smell gasoline at work at the mall in my house at all place at all times
Cola and Vinegar
Yes, gasoline works pretty good in a Coleman although it does smell.
Toothpaste works well
Diffusion
The smell of gasoline comes from the vapors it gives off. In time, the smell should disappear naturally. If you'd like to speed that process up, a good cleaning with a saddle soap will help.