Nissan 370Z Forum  

Fuel Pressure Drop? Numbes Included

Hi guys, I finally got my fuel gauge hooked up and did some pulls. At idle my fuel pressure sits at a 50-52PSI, under a 4th gear WOT run it

Go Back   Nissan 370Z Forum > Tech Area > Engine & Drivetrain

Like Tree3Likes
  • 2 Post By 1slow370
  • 1 Post By Jordo!

Reply
 
LinkBack Thread Tools Display Modes
Old 04-30-2014, 12:09 AM   #1 (permalink)
A True Z Fanatic
 
Mitco39's Avatar
 
Join Date: Aug 2012
Location: Edmonton Alberta Canada
Posts: 2,089
Drives: 40th 370z
Rep Power: 127
Mitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond repute
Default Fuel Pressure Drop? Numbes Included

Hi guys,

I finally got my fuel gauge hooked up and did some pulls.

At idle my fuel pressure sits at a 50-52PSI, under a 4th gear WOT run it drops as far down as 36PSI. Under lighter loads the fuel pressure sits anywhere between 40-50PSI.

Just curious if that is to low? I have the supplied fuel pump from Boosted Performances Kit 340lph pump. I have also ran larger gauge wire (both power and ground) to the pump.

I am just looking to see if high 30's is ok or if thats starting to get dangerous.

Thanks!

Mitch
__________________
2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
My Build --> http://www.the370z.com/members-370z-...39s-build.html
Mitco39 is offline   Reply With Quote
Old 04-30-2014, 02:04 AM   #2 (permalink)
A True Z Fanatic
 
1slow370's Avatar
 
Join Date: Aug 2009
Location: In the D
Posts: 3,607
Drives: v8 74 260z ;)
Rep Power: 485
1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute1slow370 has a reputation beyond repute
Default

it all depends on your afr's if it sniffs good your fine. your really cant control it unless you put in a return line. the tune will be set to run larger pulsewidths to make up for the drop in pressure so as long as you don't run out of pulsewidth to adjust the afr you are fine. With a return system and boost referenced regulator you can get more power out of the injectors, but if what you have works there is no need to change until you want to go bigger.
Jordo! and GaleForce like this.
__________________
ANSWER PRICE LIST
Answers - - - - - - - - - - - - - - - - $0.75
Answers (requiring thought) - - - - $1.25
Answers (correct) - - - - - - - - - - $12.50
1slow370 is offline   Reply With Quote
Old 04-30-2014, 02:32 AM   #3 (permalink)
A True Z Fanatic
 
Jordo!'s Avatar
 
Join Date: May 2010
Location: Alfa 4C
Posts: 6,394
Drives: The Ace of Spades
Rep Power: 413
Jordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond repute
Default

Here's a link to a handy calculator for checking values as an FYI, but everything 1slow said is spot on.

RC Fuel Injection
Mitco39 likes this.
__________________
Enjoy it. Destroy it.
Jordo! is offline   Reply With Quote
Old 04-30-2014, 09:46 AM   #4 (permalink)
A True Z Fanatic
 
Mitco39's Avatar
 
Join Date: Aug 2012
Location: Edmonton Alberta Canada
Posts: 2,089
Drives: 40th 370z
Rep Power: 127
Mitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond reputeMitco39 has a reputation beyond repute
Default

It does sniff good, down into the 10's under load.

Thanks 1slow, It just seemed like a big drop in pressure to me. But I am coming from the diesel world where if you lose 30% of your fuel pressure its just not going to perform like it should.

Thanks for the link Jordo!
__________________
2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
My Build --> http://www.the370z.com/members-370z-...39s-build.html
Mitco39 is offline   Reply With Quote
Old 04-30-2014, 05:00 PM   #5 (permalink)
A True Z Fanatic
 
Jordo!'s Avatar
 
Join Date: May 2010
Location: Alfa 4C
Posts: 6,394
Drives: The Ace of Spades
Rep Power: 413
Jordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond reputeJordo! has a reputation beyond repute
Default

Quote:
Originally Posted by Mitco39 View Post
It does sniff good, down into the 10's under load.

Thanks 1slow, It just seemed like a big drop in pressure to me. But I am coming from the diesel world where if you lose 30% of your fuel pressure its just not going to perform like it should.

Thanks for the link Jordo!
__________________
Enjoy it. Destroy it.
Jordo! is offline   Reply With Quote
Old 04-24-2017, 11:30 AM   #6 (permalink)
Base Member
 
Join Date: Feb 2017
Location: Florida
Posts: 11
Drives: 370z nismo stilllen
Rep Power: 3
Stillen is on a distinguished road
Default

Quote:
Originally Posted by Mitco39 View Post
It does sniff good, down into the 10's under load.

Thanks 1slow, It just seemed like a big drop in pressure to me. But I am coming from the diesel world where if you lose 30% of your fuel pressure its just not going to perform like it should.

Thanks for the link Jordo!
Do you have a fuel regulator and return system, you not suppose to loose that amount of pressure, your pressure should be solid, I have a boosted car and had a lot of problems with pressure and I fix by getting a walbro 485 and 10G wire, I deleted VVEL and set a pressure to a solid 53, tuned and car got a solid 53 even close to 7500rpm.
__________________
supercharger 13psi, 928impeller, TopGun A2A, 9lb pulley, walbro 485 pump with 10G wire with relay, FI clutch 5Puck, exhaust 3" innovate Gauges, VVEL deleted, fuel pressure set at 52, Tuned by ZTuner Harry from Bradenton Florida. 495whp on 93 and 585whp on E85.
Stillen is offline   Reply With Quote
Old 04-24-2017, 12:32 PM   #7 (permalink)
A True Z Fanatic
 
Zat_Zuma's Avatar
 
Join Date: Nov 2008
Location: Edmonton, Alberta ...eh
Posts: 1,161
Drives: 2017 Touring auto
Rep Power: 14
Zat_Zuma is a glorious beacon of lightZat_Zuma is a glorious beacon of lightZat_Zuma is a glorious beacon of lightZat_Zuma is a glorious beacon of lightZat_Zuma is a glorious beacon of light
Default

Its ok; BUT its not the ideal pressures. Pressures should be steady at all RPM's
It depends on AFR, injector duty, and heat. The stock pressure regulator is not the best for pressure control on a FI system. Fluctuating fuel pressures affect AFR ratios and can cause a lean condition if pressure drops to low. A good tune will compensate for that by keeping the injectors open longer.

Having experienced low fuel pressure at full boost and almost losing a motor,
(I guessed the stock regulator either stuck open or the fuel line was too small) I firmly believe all FI systems should have a full return system with a larger fuel inlet supply line. The stock one is less than 1/4" and is too small and if anything, increase the fuel line size to 3/8"

My plugged nickel opinion as I've been there; seen it
__________________
2017 370Z Touring Sport Auto
Been there; done that! Christ I'm old

Urethane mounts everywhere, Z1 Subframe bushings, FI LTH & Exhaust, Nismo diff, Volk GTF, Michelin PS4
Zat_Zuma is offline   Reply With Quote
Old 04-25-2017, 09:20 PM   #8 (permalink)
Base Member
 
Join Date: Aug 2015
Location: Ontario
Posts: 152
Drives: Up coming
Rep Power: 362
Ghost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond reputeGhost116 has a reputation beyond repute
Default

Also remember our regulator is at the tank so by the time your getting to the rails it's even lower. Even if ur a/f is on point could still be maxing out injectors and pump. And running something at max constantly (imo) is never a good thing


Sent from my iPhone using Tapatalk
Ghost116 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Brake pressure drop while down shift sawill629 Brakes & Suspension 9 06-15-2013 11:10 PM
Fuel pressure? Neo187H Forced Induction 43 11-28-2011 03:24 PM
Fuel Pressure? Rooskey Nissan 370Z General Discussions 0 07-22-2010 08:33 PM
Regulated Fuel Pressure Rooskey Tuning 0 07-22-2010 12:07 AM
oil cooler install (pressure drop) budz Engine & Drivetrain 14 07-09-2010 11:35 AM


All times are GMT -5. The time now is 10:51 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0 PL2