Fuel Rail Pressure Sensor help

Shaun13GT/CS · April 4th, 2010, 07:09 PM

Hey guys. So I wanted to take my car out to make sure the fuel pressure was good and everything. mell0 helped me do my dash pod and boost gauge setup (thanks andy) So I tied the boost vac line in to the fuel rail pressure sensor. I got a code saying "Fuel Rail Pressure Circuit Malfunction"

I thought maybe I pinched off a line, so I re-routed that to a differant vacuum line. Thats all set.

But the on my dads scan tool, I can datalog (kind of) And my fuel pressure seem to jump around a lot. I went WOT in 2nd and hit like 65lb, then driving around it was going like 39, 38, 42, 40, 44, 39...a couple times it hit 36, and twice it hit 34...I dont know if thats too low? So is it possible that my Fuel rail pressure sensor is shitting the bed? Could I use the one off my Dad's 03 Mach 1 to see if thats what it is? Thanks for all the help guys - Shaun

sharkbait · April 4th, 2010, 07:10 PM

Well i think its going to fluctuate as you drive. Your fuel pumps have variable speeds while mine runs full power all the time

mell0 · April 4th, 2010, 07:24 PM

yep, my fuel pressure gauge fluctuates as i drive around. usually between 35 and 45 like you said. and my bad with that setup for the boost gauge. a few people suggested it to me, and it's been working for me.

Shaun13GT/CS · April 4th, 2010, 07:27 PM

Originally Posted by mell0

yep, my fuel pressure gauge fluctuates as i drive around. usually between 35 and 45 like you said. and my bad with that setup for the boost gauge. a few people suggested it to me, and it's been working for me.

nah dude dont be sorry at all. It took 2 seconds for me to extend it. And I said I did it anyways

But, it hit 65lb at WOT, that was odd.

And you know what andy, when I was on the way back home going to my house, it started having those idle issues again too. So idk if it was because the fuel rail pressure sensor, or because I cleared the computer. But it seems to be doing okay now...every now an then its a pita.

mell0 · April 4th, 2010, 07:34 PM

Originally Posted by Shaun03GT

nah dude dont be sorry at all. It took 2 seconds for me to extend it. And I said I did it anyways

But, it hit 65lb at WOT, that was odd.

And you know what andy, when I was on the way back home going to my house, it started having those idle issues again too. So idk if it was because the fuel rail pressure sensor, or because I cleared the computer. But it seems to be doing okay now...every now an then its a pita.

damn dude, yeah besides that cold start your car seemed like it was idling fine at my house. maybe because it was colder on that trip home. you said it went away when the temps around here got warmer. maybe it is temp related?

Shaun13GT/CS · April 4th, 2010, 07:42 PM

It might be. But, the 2 days before it was fine. Not any problems. Then stuck in traffic alittle it kind of did that. I changed the line from the Fuel rail pressure sensor, so maybe thats all it needed. It should be all set anyways, if not, Ill use my dads sensor on the Mach 1 (if itll work) and see if thats the case.

yellow04GT · April 4th, 2010, 10:16 PM

mine throws the same code. mine only does it once and awile on start up. I think mine is because I removed the check valve in the fuel tank. so when I start my car I just turn the key on wait a couple seconds and that seems to help.

Eagle2000GT · April 5th, 2010, 08:46 AM

If you are data logging its supposed to read approximately 40 psi all the time. It is a computer calculated differential pressure across the injectors. An aftermarket gage is not computer corrected and will jump all over the place.

Shaun13GT/CS · April 5th, 2010, 10:43 PM

So I think my fuel rail pressure sensor is shot. Because its hard to start sometimes, and its running like shit at idle. I can smell gas. I cant find any besides the one at Autozone its Holley and its $237. This sucks

Shaun13GT/CS · April 5th, 2010, 10:56 PM

I think this is what I need to get: MOTORCRAFT 3R3Z-9F972-AA
03-04 Mustang SVT Cobra Fuel Rail Pressure Sensor MOTORCRAFT 3R3Z-9F972-AA

But will it work on an 03 GT? And from what I read its cause by hitting the rev limiter. Cause it causes all the injectors to close, and the fuel spikes and breaks the sensor. Makes sence, but I havent hit the limiter in a while, so I though. Maybe I did by accident.

Any help is really appriciated and reps!

yellow04GT · April 6th, 2010, 08:35 AM

Shaun have you moddified your fuel hat or lines at all? If you removed the little plastic line on the factory fuel hat try turning the key on the on position wait till the fuel pumps shut off then crank it over. this may help.

Shaun13GT/CS · April 6th, 2010, 02:48 PM

Yea I usually do that before I start it. It does help sometimes. But idle is my problem. I really think its my fuel rail pressure sensor. Cause it smells rich as hell at idle, and Ive heard these are common.

wishIhada5.0 · April 6th, 2010, 05:25 PM

Originally Posted by yellow04GT

mine throws the same code. mine only does it once and awile on start up. I think mine is because I removed the check valve in the fuel tank. so when I start my car I just turn the key on wait a couple seconds and that seems to help.

I just got done putting the GT pump in my car a few days ago...it wont make fuel pressure until you start cranking it over..I have no idea why lol you can sit there with the ignition on all day and it just wont make pressure until you go to start it

but back on topic..to the OP...its normal for the pres. numbers to fluctuate like that

Trick Tuners · April 6th, 2010, 05:47 PM

Originally Posted by Eagle2000GT

If you are data logging its supposed to read approximately 40 psi all the time. It is a computer calculated differential pressure across the injectors. An aftermarket gage is not computer corrected and will jump all over the place.

Correct, except its not computer calculated, its boost and vacuum referenced. Picture it like a diaphragm with boost and vac on one side, and fuel pressure on the other. When it moves toward the B/V side the pressure goes up.

Originally Posted by Shaun03GT

But, it hit 65lb at WOT, that was odd.

Are you using a boost a pump? They can cause high pressures when they are wired post FPDM.

Shaun13GT/CS · April 6th, 2010, 07:43 PM

No boost a pump.

Can anyone get back to me on the Fuel Rail Pressure Sensor? Would this be causing rough idles, and hard starts? Because it's throwing codes for "Fuel Rail Pressure Circuit Malfunction"

Trick Tuners · April 8th, 2010, 11:26 AM

Originally Posted by Shaun03GT

Would this be causing rough idles, and hard starts?

yes, it will. Replace it.

0949er · April 8th, 2010, 01:02 PM

how confident are you in your tune?

Trick Tuners · April 8th, 2010, 01:21 PM

Originally Posted by 0949er

how confident are you in your tune?

A "bad" tune could cause the frps to pop more often, but shouldn't cause these issues or the code.

Scott2001GT · April 8th, 2010, 01:24 PM

yeah I have a sensor problem too.Its a code saying fuel Rail Pressure Sensor.

Shaun13GT/CS · April 8th, 2010, 02:52 PM

Originally Posted by 0949er

how confident are you in your tune?

I wasnt at first, but now I am. I thought it was somethin totally differant. But Im ordering a Fuel Rail Pressure sensor tomorrow or Saturday

April 4th, 2010, 07:09 PM	#1
Shaun13GT/CS I Post Entirely Way Too Much 2003 Mustang GT 11.98 @ 118.68mph Join Date: Sep 2009 Location: Weymouth, MA Posts: 17,460 iTrader: 23 reviews	Fuel Rail Pressure Sensor help Hey guys. So I wanted to take my car out to make sure the fuel pressure was good and everything. mell0 helped me do my dash pod and boost gauge setup (thanks andy) So I tied the boost vac line in to the fuel rail pressure sensor. I got a code saying "Fuel Rail Pressure Circuit Malfunction" I thought maybe I pinched off a line, so I re-routed that to a differant vacuum line. Thats all set. But the on my dads scan tool, I can datalog (kind of) And my fuel pressure seem to jump around a lot. I went WOT in 2nd and hit like 65lb, then driving around it was going like 39, 38, 42, 40, 44, 39...a couple times it hit 36, and twice it hit 34...I dont know if thats too low? So is it possible that my Fuel rail pressure sensor is shitting the bed? Could I use the one off my Dad's 03 Mach 1 to see if thats what it is? Thanks for all the help guys - Shaun __________________ 2013 Mustang GT/CS 406rwhp & 397rwtq Kooks Axleback, UPR o/r X Pipe, Airaid Intake, Shaftmasters Aluminum Driveshaft. 2003 Mustang GT - Vortech 415rwhp SOLD

April 4th, 2010, 07:10 PM	#2
sharkbait Hooo Ha Ha 1997 Mustang GT 10.87 @ 125 Join Date: Apr 2009 Location: Pasadena MD Posts: 10,449 iTrader: 10 reviews	Well i think its going to fluctuate as you drive. Your fuel pumps have variable speeds while mine runs full power all the time __________________ 496rwhp 580rwtq @ 12psi 76mm Turbo 5.4 swap #turbo2v www.JPCracing.com 410-729-0005

April 4th, 2010, 07:24 PM	#3
mell0 Hardcore Enthusiast 2002 Procharged GT, STR 12.503 @ 113.08 Join Date: Feb 2010 Location: Gettysburg, PA Posts: 1,888 iTrader: 0 reviews	yep, my fuel pressure gauge fluctuates as i drive around. usually between 35 and 45 like you said. and my bad with that setup for the boost gauge. a few people suggested it to me, and it's been working for me. __________________ 2002 Procharged GT 12.503 @ 113.08 351rwhp 353rwtq Car Videos: http://www.youtube.com/user/mell00ut5?feature=mhee

April 4th, 2010, 07:42 PM	#6
Shaun13GT/CS I Post Entirely Way Too Much 2003 Mustang GT 11.98 @ 118.68mph Join Date: Sep 2009 Location: Weymouth, MA Posts: 17,460 iTrader: 23 reviews	It might be. But, the 2 days before it was fine. Not any problems. Then stuck in traffic alittle it kind of did that. I changed the line from the Fuel rail pressure sensor, so maybe thats all it needed. It should be all set anyways, if not, Ill use my dads sensor on the Mach 1 (if itll work) and see if thats the case. __________________ 2013 Mustang GT/CS 406rwhp & 397rwtq Kooks Axleback, UPR o/r X Pipe, Airaid Intake, Shaftmasters Aluminum Driveshaft. 2003 Mustang GT - Vortech 415rwhp SOLD

April 5th, 2010, 10:43 PM	#9
Shaun13GT/CS I Post Entirely Way Too Much 2003 Mustang GT 11.98 @ 118.68mph Join Date: Sep 2009 Location: Weymouth, MA Posts: 17,460 iTrader: 23 reviews	So I think my fuel rail pressure sensor is shot. Because its hard to start sometimes, and its running like shit at idle. I can smell gas. I cant find any besides the one at Autozone its Holley and its $237. This sucks __________________ 2013 Mustang GT/CS 406rwhp & 397rwtq Kooks Axleback, UPR o/r X Pipe, Airaid Intake, Shaftmasters Aluminum Driveshaft. 2003 Mustang GT - Vortech 415rwhp SOLD

April 4th, 2010, 10:16 PM	#7
yellow04GT Regular 2004 mustang GT 12.5 @115 Join Date: Feb 2008 Location: vermont Posts: 332 iTrader: 0 reviews	mine throws the same code. mine only does it once and awile on start up. I think mine is because I removed the check valve in the fuel tank. so when I start my car I just turn the key on wait a couple seconds and that seems to help.

April 5th, 2010, 10:56 PM	#10
Shaun13GT/CS I Post Entirely Way Too Much 2003 Mustang GT 11.98 @ 118.68mph Join Date: Sep 2009 Location: Weymouth, MA Posts: 17,460 iTrader: 23 reviews	I think this is what I need to get: MOTORCRAFT 3R3Z-9F972-AA 03-04 Mustang SVT Cobra Fuel Rail Pressure Sensor MOTORCRAFT 3R3Z-9F972-AA But will it work on an 03 GT? And from what I read its cause by hitting the rev limiter. Cause it causes all the injectors to close, and the fuel spikes and breaks the sensor. Makes sence, but I havent hit the limiter in a while, so I though. Maybe I did by accident. Any help is really appriciated and reps! __________________ 2013 Mustang GT/CS 406rwhp & 397rwtq Kooks Axleback, UPR o/r X Pipe, Airaid Intake, Shaftmasters Aluminum Driveshaft. 2003 Mustang GT - Vortech 415rwhp SOLD

April 6th, 2010, 08:35 AM	#11
yellow04GT Regular 2004 mustang GT 12.5 @115 Join Date: Feb 2008 Location: vermont Posts: 332 iTrader: 0 reviews	Shaun have you moddified your fuel hat or lines at all? If you removed the little plastic line on the factory fuel hat try turning the key on the on position wait till the fuel pumps shut off then crank it over. this may help.

April 6th, 2010, 02:48 PM	#12
Shaun13GT/CS I Post Entirely Way Too Much 2003 Mustang GT 11.98 @ 118.68mph Join Date: Sep 2009 Location: Weymouth, MA Posts: 17,460 iTrader: 23 reviews	Yea I usually do that before I start it. It does help sometimes. But idle is my problem. I really think its my fuel rail pressure sensor. Cause it smells rich as hell at idle, and Ive heard these are common. __________________ 2013 Mustang GT/CS 406rwhp & 397rwtq Kooks Axleback, UPR o/r X Pipe, Airaid Intake, Shaftmasters Aluminum Driveshaft. 2003 Mustang GT - Vortech 415rwhp SOLD

April 6th, 2010, 07:43 PM	#15
Shaun13GT/CS I Post Entirely Way Too Much 2003 Mustang GT 11.98 @ 118.68mph Join Date: Sep 2009 Location: Weymouth, MA Posts: 17,460 iTrader: 23 reviews	No boost a pump. Can anyone get back to me on the Fuel Rail Pressure Sensor? Would this be causing rough idles, and hard starts? Because it's throwing codes for "Fuel Rail Pressure Circuit Malfunction" __________________ 2013 Mustang GT/CS 406rwhp & 397rwtq Kooks Axleback, UPR o/r X Pipe, Airaid Intake, Shaftmasters Aluminum Driveshaft. 2003 Mustang GT - Vortech 415rwhp SOLD

April 8th, 2010, 01:02 PM	#17
0949er MM Fanatic 2004 Mustang GT 12.85 @ 114 Join Date: Apr 2010 Location: Charlotte Posts: 3,397 iTrader: 0 reviews	how confident are you in your tune? __________________ MODS: Vortech V1 T-Trim @ 7.5 PSI (tuned down) Comp Cams XE270-AH + See Garage 432 rwhp / 396 rwtq 02/27/2011 NEW VIDEOS! It takes ~$60 a rwhp (over stock) for a 99-04 Mustang GT. Do the Math PLANS ON HOLD

April 8th, 2010, 01:24 PM	#19
Scott2001GT BYAHHHH! 2001 Mustang GT 11.649 @ 119 Join Date: Mar 2008 Location: Missouri Posts: 16,639 Blog Entries: 1 iTrader: 3 reviews	yeah I have a sensor problem too.Its a code saying fuel Rail Pressure Sensor. __________________ Powered by Ford Boosted by Precision Turbo and Engine Thanks to: Wagon Wheel Performance & STL Mustangs

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