testing fuel pressure regulator on gen 2 v6 4runner (2 Viewers)

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semlin

curmudgeon
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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?
 
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...
 
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...

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!
 
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...

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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