Instead of digging the oring grommets out of the injector cap, snug the cap in a vise and pull and twist on the injector body.. the rubber will slip over the injector.. THEN dig it out. put the cap back in the vise and take a small screw driver or scribe and dig straight down along the side and split it on half..
The orings look like cut up pieces of hose, they're not actual orings, they're short & fat.. LUBE them well, makes for an easy install.
Put on the cap, then work the grommet into the cap, make sure its past the starting threads.. the closer you can get them to the bottom of the cap, the easier the install will be.
There should be a bunch of them in your kit, on account the return line cap takes 2 of them too, the brass cap..
Send me that pump.!!! lol