Fueling issues 2012 MS3

Discussion in 'Mazdaspeed 3 Troubleshooting' started by MS3Silver, Jan 4, 2020.

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  1. JohnnyTightlips

    JohnnyTightlips Platinum Member

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    My fix was just to push the plug on so it was fully seated on the fuel pressure sensor.
     
    JohnnyTightlips, via a mobile device, Feb 2, 2020
    #21
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  2. Enki

    Enki Motorhead Platinum Member

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    Sounds like the old sensor is fucked, and either your ITFP pressure regulator is out (likely, you should always change this out with the filter IMO) or your ITFP pump can't hang anymore (possible, but unlikely).
     
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  3. MS3Silver

    MS3Silver Greenie Member

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    I’ll give it a good push and see.

    Hmm alright. I’ll swap the new sensor back in and look into getting another pump and regulator. I tried replacing the filter just yesterday and no change.

    One thing I have noticed is that the pumps are compatible for both generations, though gen1’s pumps should hold at 33~psi and gen2’s should hold at 50-60psi. Am I good to just grab any oem replacement from edgeauto that says it will work for either generation? Or are the regulators different?
     
    MS3Silver, via a mobile device, Feb 2, 2020
    #23
  4. Enki

    Enki Motorhead Platinum Member

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    I don't think that's accurate. The pressure regulator controls the pressure at the HPFP (and rail, KOEO) and it would take a precise PWM pulse using known flow values for the ITFP when you key on for you to hit a lower pressure than what the regulator allows.

    Just get the regulator for now, unless you plan for more power in the future or want a higher feed pressure than what the regulator will allow (the regulator won't be able to flow enough to drop system pressure under 60 if the pump is big enough). You really only need to do something like this for PI or 6th port though, since the HPFP needs to be fed only a bare minimum of fuel pressure to operate properly.
     
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  5. JohnnyTightlips

    JohnnyTightlips Platinum Member

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    If it was me and I was already balls deep in the tank doing the filter I would have done the pump at the same time. Just to cross that off the list. It will be overkill if you never add PI but it won't hurt anything and is likely cheaper than OEM.
     
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  6. MS3Silver

    MS3Silver Greenie Member

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    So I teed up a gauge to my itfp today after work and while the key is ON, it's holding pressure at 60~psi so I don't think the pump or regulator is my issue, but my AP reads only 33psi. I've purchased an OEM rail pressure sensor(Pretty sure the one I bought/swapped earlier was a knockoff) but do you guys have any ideas as to why I would be seeing the pressure differences? Maybe a clogged fuel line?
     
  7. Enki

    Enki Motorhead Platinum Member

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    If your rail pressure reads normal at idle and cruising/wot, then I wouldn't worry about it too much.
     
  8. MS3Silver

    MS3Silver Greenie Member

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    Rail pressure is only normal at idle after the car has warmed up. During cold start, never goes above 1000~ and while cruising/WOT never above 1000. Haven't driven it since seeing that
     
  9. Enki

    Enki Motorhead Platinum Member

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    And the HPFP has been rebuilt/cleaned by someone who has experience doing it?
     
  10. MS3Silver

    MS3Silver Greenie Member

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    I wouldn't say I'm experienced.. but I felt like it was pretty straightforward. Watched some YT vids on tear downs, cleaning, and followed everything to a T. I've done 3-4 upgraded internals installations with some local speed owners in my area.
     
  11. JohnnyTightlips

    JohnnyTightlips Platinum Member

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    Well something is buggered. Can you get the motor nice and hot and see what fuel pressure it builds with key on? It should build pressure from the fuel being hot and boiling.

     
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  12. Enki

    Enki Motorhead Platinum Member

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    Well wherever you live there should be someone around that's as close to being an HPFP expert as you can get. Might want to ask around in your local nator chapter.
     
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  13. Eroler1

    Eroler1 Greenie Member

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    Not to thread jack, but Did you get the oem fuel rail sensor just the sensor? I thought mazda wont allow you to buy just the sensor and needed to buy the whole rail with it.

    Im using a autozone/Gp sorensen sensor and it works well and with 1 year warranty
     
  14. MS3Silver

    MS3Silver Greenie Member

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    Correct. Cheapest rail I could find was $90 so I bought a used sensor from a partout. Do you mind posting the part number for the sensor you’re using?
     
    MS3Silver, via a mobile device, Feb 4, 2020
    #34
  15. Eroler1

    Eroler1 Greenie Member

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    https://www.autozone.com/engine-man...njection-pressure-sensor-800-90002/295083_0_0
    currently the one im running,

    its for a 2009 chevy cobalt 2.0L
    fuel rail pressure.
    got it by matching the bosch part#

    If that sensor is failing or the connector is failing, you will get 2054psi at your AP no matter what. and that reading wont move.
    you can tell by just unplugging the connector and turn on your car (engine off) it will read 2k psi
    but if you plug it back in and it reads below 1000psi when engine is ON most of the time its working,.
     
    Last edited: Feb 4, 2020
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  16. Eroler1

    Eroler1 Greenie Member

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  17. MS3Silver

    MS3Silver Greenie Member

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    Thanks for the part suggestion. Replacing it with that part worked, for the most part. Now I can get into boost, though my fuel pressure doesn’t go above 1459psi so I didn’t wanna push it.
    I’m gonna swap in my old relief valve as I don’t believe that was my issue in the first place and see what that does.

    I checked the wiring harness as best I could with the tools I had and everything checked out so I doubt it’s a wiring issue.

    My original sensor read 2k psi, one I bought from a ms3 partout read 0psi, and one I bought off eBay worked fine up until 1000psi.
     
    MS3Silver, via a mobile device, Feb 8, 2020
    #37
  18. Eroler1

    Eroler1 Greenie Member

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    Do you have any friend near you with another speed, that can swap a known working part just to diagnose your car? like HPFP assembly and relief valve?
     
  19. Enki

    Enki Motorhead Platinum Member

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    Loosen all the bolts on the HPFP and make sure it's in there evenly (use a small mirror and look for a gap around where the HPFP meets the head). I had a similar issue once where the HPFP was in kinda sideways and would only ever make exactly half pressure.
     
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  20. MS3Silver

    MS3Silver Greenie Member

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    Yeah he’s just flaky and busy with work and school. Gonna take a look at my hpfp and do what Enki suggested.

    After replacing the seals and o-rings I did have some slight trouble getting it connected with the high pressure fuel line. I was seeing fuel leaking but after reworking it, it stopped.
    I’ll have to take my battery box and inlet pipe out as well this time to make sure I’ve got everything secured correctly.
     
    MS3Silver, via a mobile device, Feb 8, 2020
    #40
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