I recently bought the parts to rebuild EV1 (34.6# @ 43.5psi) injectors. The parts include the microfilter, flat support disk (for the injector end), and the supporting top cover (for the fuel rail end).

The reasons for replacing these parts are fairly simple:

  • Microfilter - start fresh on used injectors
  • Flat support disk - old ones were crumbling from use
  • Supporting top cover - everything else was getting changed, should change these too

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There's no issue with the microfilter, either taking the old ones out or putting the new ones in. I stuck a decking screw in my vise, point up, then screwed the old microfilter (still in the injector) onto the screw. With a little bit of wiggling and pulling, the injector pulled free with the filter still on the screw. Worked pretty slick. I can then press the new microfilter into the injector without too much of an issue.

It's the support disk and top cover I'm worried about installing. I want to ensure not only do I get these on there correctly, but I don't damage the new parts in doing so. These have a very tight fit on the injectors. What is the proper method for installing these onto the injectors without damaging them?

2 Answers 2


I had a similar worry when I replaced the pintle caps on a set of my own injectors. In my case I actually hadn't installed them far enough on to the injectors themselves and they were causing a weird idle issue. Anyways, long story short the mechanic that ended up figuring this out told me that when you go to replace the pieces it can be very very hard to do so because they are so tight. What he suggested, and the same method he used, was heating up the plastic parts by dropping them into some very hot water allowing them to expand slighty and then literally putting a massive amount of force into pushing these pieces into place.

In my case I had used quite a bit of force with them being cold and it got nowhere near the actual installation point. The slight expansion gave the tiniest bit of extra space but it was all that was needed. Best of luck to you.

TL;DR Heat the plastic bits by soaking them in very hot water and try again

  • Oh, I haven't tried much of anything yet. Your approach is exactly what I was thinking, but I'd like to ensure that's what I need to be doing. Commented Apr 18, 2019 at 22:35
  • Just thought id submit my experience. If it helps you out awesome, if not oh well. Just thought anything would help. Still, best of luck to you.
    – Techlord
    Commented Apr 19, 2019 at 0:10
  • No, thank you for being here and throwing it out here. This really is probably the way I'm going to go. It seems right. I'm just waiting to see if anyone else comes up with an answer which might be better. Thank you for answering! Commented Apr 19, 2019 at 0:24

Although I don't have experience in this, I did a quick check in one of my service manuals from Ford.

In my 2004 Ford F-Super Duty 250-550 service manual, the only special notes that I'm seeing about rebuilding the injectors are:

  • NOTICE: If the fuel injector oil inlet D-shaped O-ring is damaged, a new fuel injector must be installed.
  • Install new O-ring seals and copper washer on the fuel injector. Lubricate the fuel injector and O-ring seals liberally with clean engine oil.
  • Diagram the manual has

I understand that this may not be too much help, just thought I'd pitch in as nobody has made an attempt at answering or helping out.

Good luck!

  • This is great information and much appreciated. What's happening with me is the flat support disk and supporting top cover are hard plastic (or possibly nylon). I want to ensure I can get them onto the injector without damaging them. I had done this previously to a set of Honda injectors, but the flat support disk on a couple of the injectors kept popping off ... I don't want it ending up in the engine, so would rather have it sticking around :o) Again, thanks for the info. Commented Apr 18, 2019 at 11:22

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