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85 4runner help plzzz

Discussion in '1st Gen 4Runners (1984-1989)' started by Zappa2000, Aug 13, 2022.

  1. Aug 13, 2022 at 10:38 AM
    #1
    Zappa2000

    Zappa2000 [OP] New Member

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    Once I turn ignition on I get kinda buzzing/hissing sound (not the ignition buzzer lol) at the pressure regulator and cold start injector.
    Ok Iam at a loss.
    Changed fuel pump.
    Changed fuel pressure regulator.
    All vacuum lines are good and correct.
    Have vacuum.
    Have fuel pressure.
    Once I turn ignition on ( not cranking it) I hear fuel pump running and continues to. If I go to the fuel pressure regulator and at cold start injector I still hear that buzzing/hissing sound. Can feel fuel pumping to pressure regulator. Wth is going on.
     
  2. Aug 13, 2022 at 11:04 AM
    #2
    yotagreg8888

    yotagreg8888 New Member

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    OME lift other wise 100 percent stock
    Do you smell gas anywhere? I've been driving my 85 for 22 years and have 367K on the clock and never have hear of this,
     
  3. Aug 13, 2022 at 11:21 AM
    #3
    Zappa2000

    Zappa2000 [OP] New Member

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    Nope no gas smell or leaks. Wish I could post the video I have and you can hear what Iam talking about. But I can turn ignition on fuel pump is running and at the fuel line that goes to fpr and you hold it you can feel fuel pumping and the sound I hear is right at the fpr and cold start injector. When I try and start it it just boggs out like starving for gas
     
  4. Aug 13, 2022 at 11:38 AM
    #4
    yotagreg8888

    yotagreg8888 New Member

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    OME lift other wise 100 percent stock
    The only thing I can think of is to make sure the 2 rubber boot that go from the air box to the throttle body have no cracks.
     
  5. Aug 13, 2022 at 11:43 AM
    #5
    Zappa2000

    Zappa2000 [OP] New Member

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    Yep all brand new and tight. I have 2 other 80s runners that are running. Swapped out the with 2 other mafs and fprs as well as a new fuel pump even another ecu. Still get that whinny/buzzy sound right at that location I spoke about
     
  6. Aug 13, 2022 at 11:46 AM
    #6
    2Toys

    2Toys Imperial Star Cruiser

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    NorCal
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    a few goodies
    Since you are actually hearing a sound, and the fuel pump continues to run - I'm wondering if internally there is a leak or bypass happening in the fuel system. In most fuel injection systems, the fuel pump shuts off (engine not running, but ignition on) when the designated pressure is reached. I would be curious what the fuel pressure indicates with a direct reading pressure gage.
     
    Daddykool likes this.
  7. Aug 14, 2022 at 12:48 PM
    #7
    PhantomTweak

    PhantomTweak New Member

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    OREGON
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    None. Bone Stock. EXCEPT: Brushguard, tow hitch, both welded to the frame. It's good to have friends and a fully equipped garage!
    Toyota fuel systems, the pump keeps running when it's required conditions are met. IE: during the start cycle, the key is in STArt, whether the clutch is depressed or not. That's why it's good way to test the STArt side of the COR, the wiring back to the fuel pump, the fuel pump itself, and so forth. If all is well with those systems, you'll hear the fuel pump run when you turn the key to start, but don't depress the clutch pedal.
    Once the fuel system reaches normal pressure, the sound changes slightly. Noticeably, but not a huge change. It just gets little deeper. If you then depress the clutch pedal, it should crank over and fire right up.

    To check the run side of the COR, as well as the AFM, just turn the key to ON, or RUN, and open the vane in the AFM, even slightly. The fuel pump should run, as long as the key is ON, and the vane is open.

    Anywho, as long as one of those two conditions are met, the fuel pump will run.

    Something to check, that is often ignored, is the VOLUME of the fuel flow, not just the pressure. If there's a problem, you can have the right pressure, but inadequate volume to sustain combustion. Easy enough to check. Just put a clear tube on the FPR return line port, and put the other end into a container to catch the fuel. Put the jumper in to run the fuel pump, and time it for 1 minute. I think the amount you should get is 1/2 liter in 1 minute. If you don't get the right amount, you may well have a blockage someplace. The Pulsation damper, the fuel filter, the metal lines off the fuel hanger, and so on.
    You may want to take a look at this.

    Good fortune to you!
    Pat☺
     
  8. Aug 14, 2022 at 1:20 PM
    #8
    Zappa2000

    Zappa2000 [OP] New Member

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    Thx so much appreciated
     
  9. Aug 15, 2022 at 1:09 PM
    #9
    mousemeat

    mousemeat New Member

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    upgraded suspension, large all terrain tires
    it's a leak...the big adventure, is where ?
     
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