testing fuel pressure regulator on gen 2 v6 4runner

Discussion in '79-95 Toyota Truck Tech' started by semlin, Mar 11, 2007.

  1. semlin

    semlin rocker SILVER Star

    Messages:
    5,147
    Location:
    north of 49
    somewhere long ago i read where someone recommended pulling the vacuum line on the fuel pressure regulator on an 80 to test it. what i recall is that you are supposed to note an upward rpm change at idle when you do this. that makes sense.

    my 80 does slightly surge when i yank that line. my b-i-l's 1990 4runner v6 does nothing although there is lots of vacuum pressure. can i conclude his FPR is bad or is more needed?
  2. cam75w/ls1

    cam75w/ls1

    Messages:
    258
    Location:
    Texas, of course.
    When you pull the vacuum hose it causes the regulator to go full restriction causing the fuel pressure to jump up,richening the mixture. If you pull the hose and it does nothing then the diaphram could be bad or the regulator is stuck. Take a piece of hose and,how do I say this, uh, suck on it and see if the diaphram is good. If it's bad you'll keep getting air through the hose and in some cases,gas...
  3. KLF

    KLF Frame waxer

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    5,433
    Location:
    Southern NH
    This is one of those rare times when I'm really glad I have one of those MityVac tools. Sucking on a fuel regulator? I don't think so... blech!
  4. semlin

    semlin rocker SILVER Star

    Messages:
    5,147
    Location:
    north of 49
    thanks but isn't the diaphragm inside the regulator? in other words, what difference does it make if it's the diaphragm pierced or the regulator stuck? either way seems like a new part to me so why would i want a mouth full of gas?

    edit hey wait i have a mighty vac, but i still don't understand the point.

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