Quick fuel pressure question - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jspaeth · 01-11-2008, 09:54 PM

So fuel pressure should be 44 psi or whatever on an SR at idle....

We upgrade our fuel pump to handle an increase in boost or whatever, because more fuel needs to supplied with more air...

However, this usually results in increased fuel pressure....

My question is as follows:

Is it safe to run 13-14 psi with the fuel pressure at IDLE set at 44 psi?

I have been running 14 psi for the past year without any problem (stock T25) with a Walbro 255......I just got a Nismo FPR, so I'd like to use it to readjust my fuel pressure back to 44 psi, since I am betting that it is running very rich right now....

If I choose to adjust it back to 44 psi, will it be okay to boost past stock boost, or should I play it safe and turn the fuel pressure up a bit?

fakts13 · 01-12-2008, 01:43 AM

should be fine. nismo regulator has a 1:1 boost:fuel pressure ratio, so boost at 14psi means fuel pressure is at 58psi (if running 44psi at idle with vacuum disconnected from fpr). if you're running 44 psi at idle with vacuum connected that could be why you're running rich, since at zero vacuum you would be probably aroun 50-something psi fuel pressure.

01-11-2008, 09:54 PM	#1
jspaeth Nissanaholic! Join Date: Mar 2006 Location: Philadelphia suburbs Age: 40 Posts: 2,347 Trader Rating: (7) Rides Gallery: jspaeth Feedback Score: 7 reviews	Quick fuel pressure question So fuel pressure should be 44 psi or whatever on an SR at idle.... We upgrade our fuel pump to handle an increase in boost or whatever, because more fuel needs to supplied with more air... However, this usually results in increased fuel pressure.... My question is as follows: Is it safe to run 13-14 psi with the fuel pressure at IDLE set at 44 psi? I have been running 14 psi for the past year without any problem (stock T25) with a Walbro 255......I just got a Nismo FPR, so I'd like to use it to readjust my fuel pressure back to 44 psi, since I am betting that it is running very rich right now.... If I choose to adjust it back to 44 psi, will it be okay to boost past stock boost, or should I play it safe and turn the fuel pressure up a bit? __________________ Daily driven

01-12-2008, 01:43 AM	#2
fakts13 Zilvia Member Join Date: May 2003 Location: socal Posts: 245 Trader Rating: (0) Feedback Score: 0 reviews	should be fine. nismo regulator has a 1:1 boost:fuel pressure ratio, so boost at 14psi means fuel pressure is at 58psi (if running 44psi at idle with vacuum disconnected from fpr). if you're running 44 psi at idle with vacuum connected that could be why you're running rich, since at zero vacuum you would be probably aroun 50-something psi fuel pressure.