Fuel leakage after fuel injector installation

Discussion in 'Gen 2 Prius Main Forum' started by Kenneth Steere, Jan 31, 2026 at 9:57 AM.

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  1. Kenneth Steere

    Kenneth Steere Junior Member

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    I recently did a replacement of the valve cover, O2 sensor, PVC valve, MAF sensor and fuel injectors. Everything worked out great and I have my original fuel mileage back.

    The problem is with the fuel injectors. I installed new Denso injectors for the best quality. Yes, I did remember to remove and install the new rubber o-rings that sit in the block. One thing though, The injector to my far right, was very difficult to get into the fuel supply manifold. What should I look for and are there any tricks to getting a tighter seal to eliminate any leaks?

    Thanks!
    Ken
     
    #1 Kenneth Steere, Jan 31, 2026 at 9:57 AM
  2. Tombukt2

    Tombukt2 Senior Member

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    Ibte use the orange or pink colored o rings as many times as I do injectors hopefully once . The black o rings I replace thyre usually the uppers in the rail colored at pintle end I believe
     
    #2 Tombukt2, Jan 31, 2026 at 10:00 AM
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  3. Tombukt2

    Tombukt2 Senior Member

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    Lubing the rail o rings helps seat them in rail . Manifold end usually needs nada
     
    #3 Tombukt2, Jan 31, 2026 at 10:01 AM
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  4. Kenneth Steere

    Kenneth Steere Junior Member

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    I recall lubing the rail irings with a little motor oil. The first three(from my left to right) I could push into the rail by hand. But the one on the far right, I couldn't get it to go in by hand, so I aligned it with the rail and tightened down on it with the rail bolts. Those o-rings didn't come off the originals, but I didn't look up into the rail with a mirror.
     
    #4 Kenneth Steere, Jan 31, 2026 at 10:09 AM
  5. Kenneth Steere

    Kenneth Steere Junior Member

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    So I believe what you're saying is that you replace the black o-rings that go into the rail. The o-rings that sit in the manifold are orange.
     
    #5 Kenneth Steere, Jan 31, 2026 at 10:12 AM
  6. Tombukt2

    Tombukt2 Senior Member

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    Yes and I lubricate the o-rings that go into the rail the black ones I can't buy orange pink units . So they must be a better material or such . The replacements are black and from China Asia . So are the colored but they must be something to it . I never see the colored o rings fubar but black can be destroyed why material I'm guessing . The rail isn't crazy hot or such . Intake manifold maybe . Hence better quality o ring needed ?
     
    #6 Tombukt2, Jan 31, 2026 at 12:06 PM
  7. ChapmanF

    ChapmanF Senior Member

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    No no no no no no no oh my goodness no don't do that.

    The ends that go in the fuel rail have O rings. Put those ends very carefully into the fuel rail first, lubing and twisting as needed.

    [​IMG]
    [​IMG]

    The bottom ends that sit in the cylinder head sit in simple grommets. It's easy to get those ends in, as you install the rail with the injectors' O-ring ends already carefully inserted into it.

    If you put the injectors in the cylinder head first and then try to get the fuel rail installed over them, you take a significant chance that the O-ring ends won't go into the rail right.

    If you then try cranking down on the fuel rail bolts thinking "this'll make 'em go in", you will, if you are lucky, only destroy some O rings, and if you are less lucky, you will destroy some injectors.
     
    #7 ChapmanF, Jan 31, 2026 at 12:13 PM
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