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Thread: fuel pressure test

  1. #1

    Default fuel pressure test

    Has anyone used a fuel pressure test kit that can give me specifics where to hook this thing up? Is it a huge pain? Also, i'm assuming I can use this to test the FPR, but writeups are scarce on that one.

    Finally got someone who knows what they're doing to help tune my MS3x, last thing left is I'm diagnosing a weird ignition or fuel pump problem. In hot weather, full throttle around 4-5kRPM the engine bogs, doesn't die, just stops accelerating. Feels like it could be fuel cut, or ignition cut. Each successive gear its lower in the RPM range, and with the additional engine load when the AC is on it does it every time, when its hot it does it regardless. Definitely engine load. I'm doing plugs/wires, testing fuel, and if all checks out i'll be looking at the coil packs next, but I sold my spare set awhile ago.

    Anyway I have new plugs since my previous crap tune could could have fried the old plugs, I have NGK blues on order but wont get here till saturday, when i'll be prepping for summer classes. MiataTurbo guys think it could be fuel pump so I want to rule that out. If i'm lucky the plug wires will be the culprit, but just in case I rented a fuel pressure test kit from VatoZone. I'm getting more and more nervous about dicking with the fuel lines with the less than stellar detail ive found in the writeups of this procedure.

    Any help? I'll get photos of the fittings in a minute. Thanks in advance guys. If it's a pain then i'll just wait till my plug wires get here and go from there.

    Edit, just noticed my user name is back to blue, any PMs probably wont go through till I feed the site again.
    '94 C-Package Black & Tan | MS3x | exhintake | USDM Tein Monoflex 10/8k | My 8 year roadster evolution

  2. #2
    Another RARE Miata flyin94m's Avatar
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    I'll ask the dumb question -- What does AFR look like when (or immediately after) this happens? Is there a spike either lean or rich? I would think if it was a lack of fuel pressure, your AFR would show lean.
    Quote Originally Posted by Jeremy Clarkson
    There's no six-way traction control. There's no complicated folding metal roof. It's simpler than that. Engine in the front, drive to the rear, and a big smiling piece of meat in the middle.

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  3. #3

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    I'm assuming I tee this into the bottom line, that feeds the fuel rail?



    '94 C-Package Black & Tan | MS3x | exhintake | USDM Tein Monoflex 10/8k | My 8 year roadster evolution

  4. #4
    Team Cheap Bastard
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    PM's will still work. I'll be watching this thread since I may be testing my fuel pump/pressure very soon.

    PS
    Be sure to crack the filler cap and release the pressure before you start disco'ing lines. Gas will spill regardless, but it will
    help minimize it.

  5. #5

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    Quote Originally Posted by flyin94m View Post
    I'll ask the dumb question -- What does AFR look like when (or immediately after) this happens? Is there a spike either lean or rich? I would think if it was a lack of fuel, your AFR would show lean.
    No spike in change, followed by slowly leaning out, if I remember correctly. Not enough to be obvious or could just be hitting leaner decel cells in the VE table.

    I have logs of it, if you want to see.
    '94 C-Package Black & Tan | MS3x | exhintake | USDM Tein Monoflex 10/8k | My 8 year roadster evolution

  6. #6

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    Quote Originally Posted by sammm View Post
    PM's will still work. I'll be watching this thread since I may be testing my fuel pump/pressure very soon.

    Hey bring it over tomorrow morning, we'll test them both with this gauge, TCB approved. I could come to you also, but not available past like 2 which sucks for anyone with a regular job...
    '94 C-Package Black & Tan | MS3x | exhintake | USDM Tein Monoflex 10/8k | My 8 year roadster evolution

  7. #7
    Team Cheap Bastard
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    ^Unfortunately I have a regular job or I'd take you up on it.

  8. #8

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    http://miataturbo.wikidot.com/fuel-pump

    FYI here's the relevant writeup for anyone curious. Only thing its missing is hooking the gauge up and im not all about getting sprayed in the face with gas.
    '94 C-Package Black & Tan | MS3x | exhintake | USDM Tein Monoflex 10/8k | My 8 year roadster evolution

  9. #9

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    cleaned out my PMs, they'll work now.
    '94 C-Package Black & Tan | MS3x | exhintake | USDM Tein Monoflex 10/8k | My 8 year roadster evolution

  10. #10

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    Quote Originally Posted by Jiggerachi View Post
    Has anyone used a fuel pressure test kit that can give me specifics where to hook this thing up? Is it a huge pain? Also, i'm assuming I can use this to test the FPR, but writeups are scarce on that one.
    FWIW - This Vid helped me with figuring out my OTM.


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