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Injector Pop Pressure

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I got a pop tester finally and got around to testing all my injectors today. They say 260 bar (3771 PSI) on them but they all popped at 210 bar. These are the OEM 215 injectors. One of them was bad and did not "pop", it simply started opening up at around 200 bar and it would just stay open like a hose so that one really had no atomization going on. I will get video of it and a good one so everyone can see. I was actually hoping for a bad one so thank god I got one. I'll get video and stuff tomorrow.

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    I bought a military surplus pop tester off eBay a couple of years ago and had almost the same experience with my stock injectors. With ~113,000 easy miles on them, they all popped off at lower than spec pressures and most of them started "pissing" fuel prior to popping off.

    I took the injectors apart, cleaned them immersed in solvent in an ultrasonic tank, and then reassembled them. While I was able to adjust the pop pressures using stainless steel shims of varying thickness in the injectors, I wasn't able to stop the pissing. Apparently the tips were worn enough so they wouldn't seal properly any longer. Interestingly, my truck started and seemed to run just fine.

    I had a set of used stock injectors with only ~25,000 miles on them which I also cleaned and tested. They all popped off within spec and didn't leak prior to popping. I installed them and now have 25,000 more miles on them (~50,000 total miles). I intend to pull them out this summer and swap in my original injector bodies with new RV275 type tips.

    John L.

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    • Author

    Welllll, I think I need to get advanced..

    Welllll, I think I need to get advanced...

    A nice new set of tips would be just the ticket to go with those injector bodies!

    To adjust pop pressure when installing new injector tips (or recalibrating existing tips), I bought a metric shim stock punch set from McMaster-Carr so I could make my own custom-thickness injector shims out of stainless steel sheet stock. Going by memory, the shims need to be 10mm in diameter (CORRECTION: The shims are actually 8.5mm diameter). I was afraid of using aluminum for shims thinking they wouldn't hold up to the injector's vibrations, would eventually wear down, and the pop pressure would drift over time.

    Regards,

    John L.

    • Author

    Got say that pretty cool... :thumbup2: But I don't think you have much of a problem the pump fires much faster... :shrug:

    Yes but it still leaks and that's less than my standard lol. It would shoot just a stream no matter how hard I pumped it before so at least it's a lot better now, but I still want to get it perfect.

    A nice new set of tips would be just the ticket to go with those injector bodies! To adjust pop pressure when installing new injector tips (or recalibrating existing tips), I bought a metric shim stock punch set from McMaster-Carr so I could make my own custom-thickness injector shims out of stainless steel sheet stock. Going by memory, the shims need to be 10mm in diameter. I was afraid of using aluminum for shims thinking they wouldn't hold up to the injector's vibrations, would eventually wear down, and the pop pressure would drift over time. Regards, John L.

    I don't want to buy new tips yet, I think I can fix these. I will have to check that shim thing out.

    Looked like it wasn't spraying out all of the holes in the tip unless the camera angle was off but I didn't even see the spray in the end of the video.

    I think I can fix these.

    Based on my personal experience, you won't be able to completely stop that "pre-pop pissing." It sure can't hurt to try though. :)

    I will have to check that shim thing out.

    I'm sure you already know this, but for the sake of others reading this thread... Adding or subtracting shims only adjusts the pop-off pressure and won't help a worn tip seal any better. Best regards, John L.
    • Owner

    That's my thoughts too... If the pintle needle and the nozzle are just plain wore out then no matter what you do its not going to seal right...But since ISX had a pop bench a new nozzle and pintle needle would be a good fix for it.

    • Author

    I have nothing to lose so I am gonna try a few things lol.

    These are 5x10.25 injectors (215) so it only has 5 spraying.

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    • 1 month later...

    Thats pretty interesting. What did that rig cost you?

    I gonna have to get me a tester as well. I love this site you just learn so much more here then anywhere else. I think I know a lot until I come here then I am the true NEWBIE.....haha :thumbup2:

    He doesn't have the 24V collar for our injectors... :duh:

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