fuel pressure regulator on 3RZ; how does it work

can someone explain how the fuel pressure regulator does its job on my 97 tacoma with the 2.7L?

I understand how a FPR should work normally by closing at high throttle demand when manifold vacuum is low and opening at low throttle demand when vaccum is high BUT the vacuum line that goes to the FPR on this particular motor goes to the intake tube BEFORE the manifold where vacuum seems to always be very low.

any thoughts?

 

The 2.7 regulator works directly opposite from many others. When the engine is started, and the engine is idling, there is no excessive movement of air past the port in the intake tube, where the fuel pressure regulator is connected. This results in lower fuel pressure. (around 35 PSI) When you open the throttle, air rushing past the port in the intake tube creates a venturi vacuum. (picture blowing air across the top of a straw and watching your drink rise up the straw) This venturi vacuum allows the fuel pressure regulator to open up more, where you should see around 42 PSI of fuel pressure.

 

Mr Bama and I do not agree on this question. http://www.tacomaworld.com/forum/technical-chat/289238-p0171-code.html

I maintain that the FPR (2.7 and 3.4) is "fixed" and not affected at all by any engine running condition. And further, that the hose connection upstream of the t-body is only there to direct a fuel leak (leaking FPR diaphragm) to the intake as a fire safety measure.

This lack of vacuum can be easily seen with a gauge plugged into said hose under any running combination of RPM and throttle position. I have checked this myself on the 3.4 and for it to be any different on the 2.7, I would really have to see it or at least hear of an observed number or any other supporting evidence for that matter.

 

If this FPR fails,would cause a cranking issue,like flooding trying to cranks it?