I just pulled my fuel pump, and installed a new Delco pump - however, I have noticed a few things and am not sure what to do.
First, the rubber isolator - it seats into the bottom of the pump, however, there is extra or more space between the pump and the isolator and the sending unit chassis. It is hard to keep the isolator from moving around. I have pushed the pump down further (but making sure that it was still seated into the pusaltor) and using the rubber foam insulation around the pump itself have attempted to 'tighten' things up.
SHould I be concerned? Can I run the pump without the isolator.

Second. How important is the diffuser? (the pancake flat platic circle that goes between the isolator and the sending unit housing and the strainer)? Can I run without it?
TIA
Andrew