Blazer fills slowly and over runs easy. Assume there is a screen before tank? Girlfriend had lost cap and had stuffed napkin in. Grrrrrr. Anyway, can i just undo filler hose at the tank and clean this out? 2004 blazer.

 

No screen in there but there is a ball, kind of like a reverse check ball but not. This is the anti-siphon device. I highly doubt the fill line would be clogged. Maybe the vent line but doubtful, too.

Crawl under there and take a look at the soft hoses, a kink in either would cause you problem.