Well this is slightly off topic as its on my turbo bike project not my 7 but anyway...
Bike throttle bodies off gsxr 600 combined with subaru wrx injectors. The bottom o-ring for the bike setup has large OD while the subaru injector has o-ring with small OD. Used the bike ones and it works fine (ID is ok) but as soon as it sees boost it pops the o-ring out. As I see it I have 3 options:
1. Washer that fits over the nozzle of the injector but not over the stem and presses down on the o ring (except the injector might not seal on the oring if the washer is taking all the pressure)
2. Bush that reduces the injector hole in the throttle body to the same as the wrx and then use wrx o rings (probably a better solution).
3. Sleeve that goes around the injector and puts pressure on the oring (but that pressure would probably also be on the electrical connector bit which probably isn't a good idea).

I've probably explained all that badly so here's a pic. The 2nd injector across has the displaced o-ring.


[Edited on 14/7/17 by luke2152]

You are using PhotoBucket, not able to see the image until you pay them!

Didn't know photobucket was doing that. Oh well changed it now

Thread on the subject: https://www.locostbuilders.co.uk/forum/8/viewthread.php?tid=209488
About your problem.On all the injectors I have, there is a shoulder over the O ring. Weird!

As above the O ring is usually in a cut out on injector, so when pushed in the O ring is compressed inside the mounting point.

I can't see that set up you have ever working reliably tbh.

Yep seems obvious in retrospect. WRX injectors use grommets 9mm ID and 16mm OD. Gsxr uses 13mm ID and 21mm OD. The tapered but not properly stepped bit of the WRX injector fitted into the gsxr grommet but that was never going to hold boost.
Fortunately the gsxr TB has a 14mm bore below the 21mm so I might be able to find a grommet of 9mm ID and 14mm OD. Else I can just drill it out to 16mm and use a WRX grommet.