Ever wonder what's inside an MFI fuel injector?

[Zeke]

In order right to left:
Body, screen, metering orifice, keeper, spring, plunger and the end where the fuel sprays.

[david c.]

Neat. Considering all that pressure, those are some mighty small pieces.

[michel richard]

an the injector be put back together ? i.e. can they be taken apart for cleaning ?

[304065]

Thanks!

Why did you take it apart?

[Zeke]

Originally posted by john_cramer
Thanks!

Why did you take it apart?

John, that one sat in a port that was full of rain water for long enough that the surface of the plunger and it's plate were erroded by rust. The spray pattern would have been mitigated at best. I thought it would be best if I sacrificed it to see better how to clean them.

My conclusion is to soak them and or ultra sonic clean them much as Warren has said, but also blow air and cleaner backwards up the injector to make sure the screen in clean.

I have made a small tool to lift the plunger while doing this. Obviously, one does not want to stress the tiny spring by lifting too much.

I think it is possible to remove and replace the innards. The process would be similar to rerolling the lip on the back of a dashboard intsrument, but it would take a lathe to accomplish.

I don't know if the two injection service houses frequently mentioned on the board can and do actually rebuild these things, but it's time someone figured out how if they don't. Again, obviously, one does want parts being sucked into the intake, so this has to be done well. The things are way overbuilt, typical German engineering, IMHO.

Additional thought: I do believe the innards could be improved and be placed in the body. With a little injection research, I bet one could find alternative parts or even a complete injector that could be adapted to the body.