I have totally rebuilt several 748 injectors from scratch and renewed all the small screws and nuts in the process using stainless steel ones and all the rubber seals etc.. I am not sure what you mean by plastic sleeve seals though as there are none. There are O rings in the base of the injectors and also in the injector bodies where the butterfly mechaism is sealed in the body. Here's a couple of photos of the injectors reaching completion. Not sure if this helps in showing what parts you want to replace.
The OP is talking about the actual injectors. Your pictures show the throttle bodies which the injectors are fitted into - the green plastic bits with the fuel lines attached.
For one set of injectors I pulled them out and had them ultrasonically cleaned and test by a specialist. They were returned with new injector O rings ready to fit and were within the test limits. Pulling the injectors out needs a certain amount of care and plenty of WD40 or the like to ease them out. After that you can test as per above or replace. The small metal plates that hold them in can be very difficult to remove as the screws that hold them in are very soft, make sure you have a good fitting tool if you intend to actually pull out the injector. I believe some cars had this type of injector fitted so you may not have to necessarily go with a genuine Ducati sourced part. After that they do crop up on eBay. I assume you feel you have an injector problem as opposed to possibly a fuelling problem or something else. All the injectors I have rebuilt have always been pretty much perfect inside apart from a decent clean and new O rings. Hope this helps.
Thanks Red998. As Derek understood, I refer to the injector. Removing the injector from the throttle body - and replacing the o-rings and back-up ring is straightforward. A little fiddly though, I agree. I'll Google and eBay some images to identify the automotive applications for the Weber injector. Thanks for the prompt. When you rebuilt the injector, did you take it apart, checking the 'needle and nozzle' and replacing the seals (perhaps plastic sleeves with an o-ring energiser) inside? If so, how did you split the body please? the 'mechanical' diesel injectors on my car had hexagons - so it was like unscrewing nut and bolt, that were extremely tight. i'll remove the black plastic cap at the top of the green body. Maybe the 'rod' will shake out. Will probably need to drill out the metal pin from each side and replace when its rebuilt. Thanks David what I suspect may be inside the injector - if its not close metal-to-metal bearing fits
The injectors are a one piece item and cannot be dismantled, hence why I had them cleaned and tested. As you can see there are two O rings to be repalced and these are easy enough to source. The injector is a tight push fit in the housing and I release mine by intially carefully turning with a close fitting spanner and then ease them out with a pair of mole grips whilst protecting the injector with several layers of cloth. If you are removing any of the roll pins you will find that they should come out pretty easily but a suitable punch should be used. I tumbled my throttle bodies in order to clean them and they came out quite clean despite years of dirt accumulation. Bear in mind if you disturb any of the throttle or TPS settings then they will need to be reset and possiby the idle and balance corrected. The photo is actually from an eBay item currently at £55, a better route if you need to totally replace an injector.
