Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Go Back   Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum > General > Tech Talk > Engine Tech

Engine Tech Technical discussion related to all relevant engines such as KA, SR, RB, CA, 2JZ , and Lx series.


Reply
 
Thread Tools Display Modes
Old 11-14-2011, 05:57 PM   #1
jontron5000
Zilvia Junkie
 
Join Date: Sep 2010
Location: So Cali Baby!
Age: 27
Posts: 378
Trader Rating: (6)
Feedback Score: 6 reviews
Fuel Pressure Regulator + SR20DET Swap

Hey guys,

I have completed my SR20DET into my S13 hatch a few months ago and it drives around perfectly fine, minus the idling problem here and there. I have been noticing very poor gas mileage (17-20 mpg, city/hwy driving, little to no boosting at all and shifting around 3500 rpm). I have seen people posting their fuel efficiency with nearly the same exact setup and they are up in the high 20's to low 30's.

Upon researching this issue, people have suggested to changing to an aftermarket adjustable fuel pressure regulator when upgrading the fuel pump to a Walbro 255 high flow (A pump I am currently running with the stock FPR). I do notice a small hit of gas near the front of the car which people have claimed is an issue related to the FPR.

So my question is, is replacing the stock FPR to an aftermarket AFPR when installing a high flow fuel pump with the SR20 swap an important step of the swap I have missed? According to the swap write ups I followed when doing this install, none of them had mentioned anything about FPR so I would like some input on the issue

Thanks!
__________________
jontron5000 is offline   Reply With Quote
Sponsored Links
Old 11-14-2011, 06:29 PM   #2
jr_ss
Post Whore!
 
Join Date: Dec 2005
Location: Fl
Posts: 4,325
Trader Rating: (32)
Feedback Score: 32 reviews
Send a message via AIM to jr_ss
It's always good to have a means to adjust fuel pressure with an upgraded engine. On a bone stock swap it isn't necessary, but not a bad idea. When I did my swap I had a walbro and had an intake, FMIC, full exhaust and an upgraded wastegate running 11lbs on my stock FPR. I would get about 26mpg on the highway like that.

Now since you have an upgraded walbro I have heard of running higher than normal fuel pressures because you have a new pump/old regulator and possibly the diaphragm has gotten weak over time and has trouble with the new volume/psi of the fuel. I'd suggest putting a gauge on your fuel line and see what pressures you're running with and w/out vacuum and go from there.
__________________
VVL S14 in the works...
jr_ss is offline   Reply With Quote
Old 11-14-2011, 06:46 PM   #3
jontron5000
Zilvia Junkie
 
Join Date: Sep 2010
Location: So Cali Baby!
Age: 27
Posts: 378
Trader Rating: (6)
Feedback Score: 6 reviews
Quote:
Originally Posted by jr_ss View Post
It's always good to have a means to adjust fuel pressure with an upgraded engine. On a bone stock swap it isn't necessary, but not a bad idea. When I did my swap I had a walbro and had an intake, FMIC, full exhaust and an upgraded wastegate running 11lbs on my stock FPR. I would get about 26mpg on the highway like that.

Now since you have an upgraded walbro I have heard of running higher than normal fuel pressures because you have a new pump/old regulator and possibly the diaphragm has gotten weak over time and has trouble with the new volume/psi of the fuel. I'd suggest putting a gauge on your fuel line and see what pressures you're running with and w/out vacuum and go from there.
Can the increased volume/psi of fuel also affect performance in one way or another?
__________________
jontron5000 is offline   Reply With Quote
Old 11-14-2011, 10:20 PM   #4
rcdad123
Zilvia Addict
 
rcdad123's Avatar
 
Join Date: Jul 2011
Location: san diego
Posts: 639
Trader Rating: (0)
Feedback Score: 0 reviews
air fuel ratio can change by changing the fuel pressure. higher pressure will make the engine run richer and lo pressure will make it lean. upgrading the fuel pump to a higher flow should not make any changes to the afr, but if the new pump produces more pressure than the old pump, the final pressure to the fuel rail will be higher than before even if you did not adjust the fuel pressure regulator, which in turn will make the engine run richer. the only reason i use adjustable fuel pressure regulator on turbo engines is because i like to run 75 psi of fuel pressure.
rcdad123 is offline   Reply With Quote
Old 11-15-2011, 12:46 AM   #5
KiLLeR2001
Post Whore!
 
Join Date: Jun 2007
Location: オーランドフロリダ
Posts: 6,105
Trader Rating: (28)
Feedback Score: 28 reviews
Quote:
Originally Posted by rcdad123 View Post
the only reason i use adjustable fuel pressure regulator on turbo engines is because i like to run 75 psi of fuel pressure.
Really? You run DOUBLE the psi of a stock SR setup?
__________________


NissanPure.com
KiLLeR2001 is offline   Reply With Quote
Old 04-01-2012, 08:59 PM   #6
jontron5000
Zilvia Junkie
 
Join Date: Sep 2010
Location: So Cali Baby!
Age: 27
Posts: 378
Trader Rating: (6)
Feedback Score: 6 reviews
UPDATED: To anyone curious, I ended up purchasing a Megan Racing Adjustable Fuel Pressure Regulator and the Isis Fuel Pressure Regulator Adapter. It's been about a week and my SR20 runs SO much better. When driving around town, I do not have to rev the engine as high or boost to keep up with traffic (A problem I was experiencing with bogged and poor acceleration). When spooling, the car feels much faster and I can actually feel the turbo kick in, I am very happy now.

The car no longer emits the smell of gasoline anymore, either up near the engine or out of the exhaust.

In terms of fuel efficiency, on the highway i was only averaging 23 mpg max before changing my afpr. But on half a tank, I was about to travel from where I live to LA (about 50 miles each way) a total of 4 times before having to refuel. According to the math, I calculated about 29.6 mpg hwy, but mind you I was only traveling around 62-65 mph on the highway.

I hope this helps!
__________________
jontron5000 is offline   Reply With Quote
Old 04-02-2012, 06:34 PM   #7
ShadowMan
Zilvia Junkie
 
ShadowMan's Avatar
 
Join Date: Jul 2011
Location: oceanside, CA.
Posts: 534
Trader Rating: (4)
Feedback Score: 4 reviews
Thanks for the update, I'm about to tackle this same problem. My issues are pretty much identical to yours. What made you go with the megan racing fpr? just out of curiousity.
__________________
in any situation....thou shalt blaze
ShadowMan is offline   Reply With Quote
Old 04-02-2012, 06:52 PM   #8
jontron5000
Zilvia Junkie
 
Join Date: Sep 2010
Location: So Cali Baby!
Age: 27
Posts: 378
Trader Rating: (6)
Feedback Score: 6 reviews
It pretty much just boiled down to price. Also because it comes with a built in gauge which is a nice feature.
__________________
jontron5000 is offline   Reply With Quote
Old 04-02-2012, 07:16 PM   #9
cotbu
Nissanaholic!
 
cotbu's Avatar
 
Join Date: Sep 2005
Location: DE
Posts: 2,403
Trader Rating: (3)
Feedback Score: 3 reviews
Most of the Megan Racing Fuel Pressure regulator I've seen, haven't been rising rate regulators! Maybe they copied a new regulator or something? Which model do you have?
__________________

LoverTechnologies "Half Broken Things!"
cotbu is offline   Reply With Quote
Old 04-02-2012, 08:07 PM   #10
jr_ss
Post Whore!
 
Join Date: Dec 2005
Location: Fl
Posts: 4,325
Trader Rating: (32)
Feedback Score: 32 reviews
Send a message via AIM to jr_ss
I'd suggest a Tomei/Sard/Aeromotive unit... Tested, tried and true.
__________________
VVL S14 in the works...
jr_ss is offline   Reply With Quote
Old 04-03-2012, 05:43 PM   #11
Kingtal0n
Nissanaholic!
 
Kingtal0n's Avatar
 
Join Date: Jul 2005
Location: South Florida
Age: 31
Posts: 1,842
Trader Rating: (10)
Feedback Score: 10 reviews
Send a message via AIM to Kingtal0n
The computer is responsible for how much fuel gets injected. The mixture is burnt, and should be tested by the oxygen sensor, which the computer will watch and attempt to control by altering between rich and lean mixtures as you drive.

If the oxygen sensor is connect properly, the ECU will do this job, and fuel pressure will have very little say in the final fueling of the engine. Altering the fuel pressure changes the amount of fuel that will come out of an injector but the computer has control over the amount of time the injector spends open, which also affects fueling. Having more fuel pressure should cause the ECU to compensate by reducing the injector ON-TIME values, it will learn to keep the voltage of the oxygen sensor swinging from 1V-0V while you drive.
Kingtal0n is offline   Reply With Quote
Old 04-04-2012, 03:22 AM   #12
zurud
Zilvia Member
 
Join Date: Aug 2009
Location: evansville, in
Posts: 277
Trader Rating: (4)
Feedback Score: 4 reviews
Quote:
Originally Posted by jontron5000 View Post
UPDATED: To anyone curious, I ended up purchasing a Megan Racing Adjustable Fuel Pressure Regulator and the Isis Fuel Pressure Regulator Adapter. It's been about a week and my SR20 runs SO much better. When driving around town, I do not have to rev the engine as high or boost to keep up with traffic (A problem I was experiencing with bogged and poor acceleration). When spooling, the car feels much faster and I can actually feel the turbo kick in, I am very happy now.

The car no longer emits the smell of gasoline anymore, either up near the engine or out of the exhaust.

In terms of fuel efficiency, on the highway i was only averaging 23 mpg max before changing my afpr. But on half a tank, I was about to travel from where I live to LA (about 50 miles each way) a total of 4 times before having to refuel. According to the math, I calculated about 29.6 mpg hwy, but mind you I was only traveling around 62-65 mph on the highway.

I hope this helps!

So what's the pressure before and after you put on regulator? I checked mine ,after and before puttting on aftermarket regulator the pressure is the same. Pretty useless for me to put aftermarket regulator on, waste of $200.00.
zurud is offline   Reply With Quote
Old 06-05-2012, 10:06 PM   #13
slideways SR20
 
slideways SR20's Avatar
 
Join Date: Jun 2012
Location: Wilmington, NC
Age: 19
Posts: 11
Trader Rating: (0)
Feedback Score: 0 reviews
megan FPR

sorry to bring up the dead thread but How has it been running with your megan FPR? i did my swap about a month ago and it is running rich now. i have a walboro 255 with stock FPR and i am thinking the old FPR isn't holding up and im trying to decide on a new one
slideways SR20 is offline   Reply With Quote
Old 02-27-2013, 07:55 AM   #14
zneubauer
Zilvia Addict
 
zneubauer's Avatar
 
Join Date: Jun 2011
Location: Florida
Age: 23
Posts: 640
Trader Rating: (7)
Feedback Score: 7 reviews
Quote:
Originally Posted by zurud View Post
So what's the pressure before and after you put on regulator? I checked mine ,after and before puttting on aftermarket regulator the pressure is the same. Pretty useless for me to put aftermarket regulator on, waste of $200.00.
maybe it comes out of the box on a stock setting so you might need to adjust it. just a thought.
zneubauer is offline   Reply With Quote
Old 02-27-2013, 09:02 AM   #15
Croustibat
Zilvia FREAK!
 
Join Date: Aug 2011
Location: France - Toulouse
Age: 33
Posts: 1,221
Trader Rating: (0)
Feedback Score: 0 reviews
Quote:
Originally Posted by zneubauer View Post
maybe it comes out of the box on a stock setting so you might need to adjust it. just a thought.
Do you ever read the date of the last post before adding a useless comment to an 8 month old thread ?
Croustibat is offline   Reply With Quote
Old 02-27-2013, 02:01 PM   #16
fliprayzin240sx
I </3 VA
 
fliprayzin240sx's Avatar
 
Join Date: Aug 2002
Location: Ass Crack of Hamptin Vagina
Posts: 17,441
Trader Rating: (18)
Feedback Score: 18 reviews
Send a message via AIM to fliprayzin240sx
Quote:
Originally Posted by zneubauer View Post
maybe it comes out of the box on a stock setting so you might need to adjust it. just a thought.
Considering most aftermarket fpr are universal units and every car runs different pressures, I highly doubt that its good for your car right off the bat.
__________________

If you think Zilvia has too many assholes...
CLICK HERE!!!
fliprayzin240sx is offline   Reply With Quote
Old 02-28-2013, 01:47 AM   #17
steve shadows
Premium Member
 
steve shadows's Avatar
 
Join Date: Aug 2003
Location: LA and OC
Posts: 8,208
Trader Rating: (5)
Feedback Score: 5 reviews
Send a message via AIM to steve shadows
^^^ Yeah...don't do that...

You need to check it and set it with an out of the box new fully adjustable fuel pressure regulator no matter what the documentation says that comes with it...

Also if you don't need it, which most people should not need one...then don't buy it. I ran stock Fuel Pressure Regulators on 400-500 hp srs around here for years...including my own. In fact I had an aeromotive and a stock one in great shape and ended up shelving the aeromotive. Didn't have problems. Just a thought for those on a budget.

Of course make sure your stock one is working properly both AT idle and UNDER load!
steve shadows is offline   Reply With Quote
Old 01-11-2014, 03:06 PM   #18
afracer
 
Join Date: Mar 2007
Location: Texas
Posts: 27
Trader Rating: (0)
Feedback Score: 0 reviews
Bumping an old thread, sorry for that, but I'm having some really really weird fuel pressure issues.

Car started running rich and very erratic; AFR's are all over the place, I've finally picked up a fuel pressure gauge and have narrowed it down to the FPR after replacing a lot of things. Here's where it gets tricky...

Car has a Nismo adjustable FPR. Hooked up the gauge to the fuel rail inlet and this thing is getting 90 psi according to the gauge, wow that explains the richness. Moving the adjustment screw in either direction has absolutely no effect on the fuel pressure.

So I bought another stock type brand new FPR (non-adjustable), and it also shoots straight to 90 psi and just stays there regardless of vaccum line on/off/plugged, whatever.

What the hell could be causing this problem?! Obviously the fuel pump is working like a champ. Could have a bad gauge I guess, even though it is also brand new. This is really frustrating, I've never encountered anything quite like this before. I might try to get another gauge to see if the one I got is a dud, cause this makes no sense.
afracer is offline   Reply With Quote
Old 01-11-2014, 03:17 PM   #19
brndck
Premium Member
 
brndck's Avatar
 
Join Date: Jun 2003
Location: north san diego county, ca
Age: 32
Posts: 7,922
Trader Rating: (104)
Feedback Score: 104 reviews
Send a message via AIM to brndck
My first guess is that you have a restriction or blockage in the return line to the tank.
__________________

http://outslidersandsmokeproduce.blogspot.com/
Quote:
Originally Posted by Mannykiller View Post
it'll fit JANK.. and no one likes Jank except Broke ass zilvians.
brndck is offline   Reply With Quote
Old 01-12-2014, 04:58 PM   #20
afracer
 
Join Date: Mar 2007
Location: Texas
Posts: 27
Trader Rating: (0)
Feedback Score: 0 reviews
Hmm, sounds like a plausible hypothesis...I guess I could check by disconnecting the fuel return line and routing it to a gas can, then start the car up and see if I can control the fuel pressure with it like that. If not then obviously it's not a blockage problem.
afracer 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

Forum Jump


All times are GMT -6. The time now is 06:15 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
vB.Sponsors
Copyright © 1998 - 2014, Zilvia.net™