replacing fuel pump on blazer, can't get retaining ring off

Yep, hammer harder....some of them are quite difficult to get off. Of course, it's easier with the special tool, but I've always been able to get them off with a punch.

Ian

Is the ring threaded (sort of)? You use the punch to spin it, right?

Yeah, what Ian said. I had to beat the snot out of mine, and was just about to break the tab off because of the force I was using before it let go. This was after 2 hours of PB spray soaking. Bad location for crap to collect and cause rust. Once it breaks loose, before you pull it off, I recommend blowing around the ring with compressed air to get the residual rust and road grime out so it doesn't fall into the tank. Also, be gentle when pulling the unit out, as the float makes it a tight fit.

Big Chris

if there's more than one tab, alternate between them with the hammer and drift.

NEVER FORCE ANYTHONG, get a bigger hammer. Try to avoid sparks.