I always coat the grommet with dielectric grease, I suppose any lite grease would work, before installing. I’ve also made a rounded wooden dowel, so I don’t cut it, to help force it in place.
It sorta the competitor shop owner was complaining about how it was to install fuel lines. Then Had him try in my shop and seen he was pushing instead of pulling the lines. I showed how I did it and he went away a happy camper.
I have done a lot of these. IF the grommet has the three hoses in. Take out the hoses and it will go in much easier. Even still a bit of oil on rubber helps. Cut hoses on angle to easily fit in grommet, if needed coat hose with oil help here. The one hose needs to go well into take with filter on it. The other two need to just get inside tank a bit like 3/4" or so.
Well... It was actually pretty easy. Required no lube this time and just my luck it leaks out of the top. I think maybe all the aftermarket ones do maybe.