Nismo3112 and I swapped a 3.5 into my 96. Using an ebay fpr, the gauge showed about 20psi when the key was turned to "ON". I ditched the ebay fpr because it was showing about 39-44psi (needle was constantly twitching) and wouldn't go any higher regardless of tweaking.

A week later, I swapped the fpr for a Nismo fpr and BlackbirdVQ installed a Walbro 255lph fuel pump. When I turn the key to "ON", my in-line gauge shows 20psi.

Is 20psi when the key is turned to "ON" normal? Or is it indicative of a bigger problem?

 

your pump seeing 12v? Hows your grounds? I know the stock 4th gen pump puts out 43 psi when swithced from off to on.

 

Maybe try adjusting the FPR until the gauge reads 43psi (fsm) when switched to "on"

 

The pump doesn't create pressure, the FPR does. It doesn't matter how strong a pump is; if the FPR isn't providing enough resistance there won't be enough pressure.

 

Should a vacuum source be connected to the FPR? I'm getting conflicting answers reading past threads. Here's how I've adjusted my FPR.

1. Cap vac source on IM and cap the FPR
2. Start the car
3. Set fuel pressure to 51psi

 

yea i believe you need to have a vacuum on your FPR.
http://www.type2.com/bartnik/reg.htm
that is a link i got from google, maybe there is a better description of the vacuum source function, but i didnt find one.

i wrote up a thread about how the FPR and FMU all work, whether it is both of them used or just one.
http://forums.maxima.org/showthread.php?t=515099

 

Well the argument for vacuum being supplied to the FPR is that the pressure differential on either side of the injectors should be similar at all throttle angles. At idle/high vacuum the pressure is lower, and as pressure is increased in the LIM due to the decreasing vacuum, fuel pressure should increase accordingly. To tell you the truth, either way is fine from what i've seen.

As for the 51 PSI thing, that number is completely arbitrary and has no factual basis other than the fact that the A33B/A34 run constant 3.5 bar. I see no reason why this is necessary when using the 3.0 ECU. I can understand why you see conflicting info, because i was one of the main proponents of it. I need to amend the 3.5 swap sticky to clarify.


P.S. If you want to advance your ignition timing by increasing injector flow and removing fuel with a AFC that's an entirely different matter.

 

thanks I know this was helpful for me