Just thought I would post a quick find, since it took me forever to locate. I was trying to clean the injectors on my 2.8 today; however, the little plastic caps on the tip of the injectors kept breaking or cracking. You need these caps on the injectors or it won't seal properly and you will be leaking gas.
Local auto part stores carry the pintle cap and seals. Part number 274081 which is BWD. Unfortunately one set does 1 injector, so you need to purchase 6. But at only 3.99 each, who can complain.
You can take your old caps off with a box cutter blade by cutting carefully cutting down the sides of the cap.
Putting the new caps on requires a lot of force to get them to seat.
Here is a youtube video i found which demonstrates how to put on the new caps and seals. Its not our exact fuel injector, but the method is the same.https://www.youtube.com/watch?v=4vwyuxuzcko
I don't recommend using the socket and hammer (like in the video) to press the caps on the injector as you could damage it. You strength of your hands should be enough, but you might want to wear some decent gloves.
Maybe this will help someone.