Get it over with, save money and time, keep it simple, proven.
https://www.yotatech.com/forums/f116.../#post52415602

 

that's the one i bought, it fit my 94 4runner 3vze perfectly, maybe the thread is different on the 4 banger

 

The 12mm banjo bolt is used at the fuel pressure regulator.







The LCE banjo bolt is smaller (10mm?) to be used on the CSI.

 

On the left is the eBay one, on the right is the one that fits in the line for the cold start injector:

 

Oh, didn't know some folks put the gauge on the fuel pressure regulator banjo bolt.

 

after looking back over thread i didn't realize they were using the csi port, my bad, any way this is how i checked fuel pressure

 

 

So I finally got off my butt and put a pressure gauge on my Cold Start Injector port, (took long enough I know, sorry to bring up an old topic), and I am showing 42 psi at idle. I don't think to play with the throttle body at the time so I only checked idle, but I believe that is right on the money as far as pressures go. Please correct me if I am indeed wrong. Thank you all for the assistance, I'm a slow learner, and appreciate the help.

 

That might be too high. The spec at idle is 33-37psig. The spec at idle with the vacuum line removed from the FPR is 38-44psig. http://web.archive.org/web/201003261...87fuelpump.pdf

I'd re-run the test, removing the vacuum line. If you don't get a change on your gauge, something could be very wrong with your fuel pressure.

 

Just checked mine, 28psi at idle after operating temp is reached. I have a new OEM pump & FPR too. Would being a little below spec cause a rough idle? When I turn car off, gauge goes up to 35psi and holds there for a while. Is that normal?

 

While your fuel pressure does seem low, your gauge may not be that accurate anyway. The MFI system is designed to increase the injector open time when there is "too much" oxygen in the exhaust, so that should adjust for it. You could test that by looking at the Ox1 signal; it should flop back and forth between about 0.3 and 0.9 volts 8 times in 10 seconds If you've reached the "limit" of what the MFI can adjust, the O2 sensor will sit on one side. (But then again, THAT should throw a code.)

Your FPR is designed to keep the pressure ACROSS the injectors constant. So when there is vacuum in the intake, the fuel pressure is lower. When the vacuum goes away, if your pump keeps running for a second or so the FPR will raise the pressure to accommodate for "no vacuum." Mine doesn't do what you describe, but you have a newer fuel pump (better check valve) so the pressure rise doesn't surprise me.