Fuel Pressure Q's

al35thsc

Registered User
So, Mike (35thsc) and I went to a local speed shop. Mike needed some pushrods for an engine he is building. Well I was there and thought it would be a good idea to install a fuel pressure gage at the rail, quick 20 minute install . Anyway, long story short, I bought a BBK liquid filled 0-60 gage and after 3 trips to different places we bought some brass fittings that worked.

Now this is the part thats weirding me out. Once installed, it read 30 PSI, with the vaccuum line on the FPR. If I revved it, it would go up to 40 so fuel pressure DID seem to go up with boost. So I drove home and when I got here I decided to check for leaks. The car ALWAYS has a stutter after a long drive...it kinda lopes and misses. Fuel pressure was down to about 20-22 and the car was warm (usually that warm around the O and R). Then after I drove it at night from the gf's place, it read 30.

Mike and I put in 255 lph and 36 lb/hr on my car, but never replaced the FPR. I'm not too sure if I have vac leaks but it idles around 17-18 inches of Hg. I have the C&L 76mm with the 36-38 sample tube. Its kind of scaring me a little. The fuel filter was replaced 3-4 weeks ago and the old one was pretty fugged.

Anyone know where my pressure should be and why mine is so low???

Alex
 
AHHHHH.

There could be alot of possibilites here. Perhaps wrong fittings. I am wanting a gauge for my fuel rail. Are there any other options besides Auto-meter #2179 with adapter 3280. Will these hook to stock rail and work correctly?
 
Ford manual states with the key on and engine off the pressure should be 35-40 psi.
Causes for low pressure are.
1.Clogged fuel filter.
2.Bad pump.
3.bad pressure regulator.
4.Leakage at the fuel pump check valve.
5.Fuel injector or injectors leaking.
 
Here is what it should KOEO.
Gauge with 45 degree fitting.Autometer.
I run mine at 38.5


Al35sc I was just tying to be funny on the other thread,sorry
Randy
 

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COOL

Randy are those the right #'s I want a white one and do you have to have the adapter for the stock schrader valve. How does yours work? Are you happy with it I have heard there is only a small drop of 4 at wot is this correct.
 
stocker 89 yes they are right.

auto meter 2179 for white face.

2173 black face.

adapter 3280 1/16 pipe in to 5/16 taper thread.

Got the 45 degree fitting at the local hardware.

$55.80 for the complete set up.Summit racing 1-800-230-3030
 
Everyone says WHY? you can't even see it when driving.

Yeah Jockos can get pressure gauage for me 33.00 Gonna pick one up in a few weeks. adapter is 7.00.

Well Mike and Randy what #'s should I be watching for on a stock 3.8 SC motor at /start up / when reving throttle / and at idle/. If I get one I need to know what to expect and be looking for. Can you use this with a fuel injector drop tester ?

Is A adjustable FPR worth it ? Or should I stay with stock one?
 
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The fittings are the correct ones, Mike knows his shi...stuff. Filter was replaced a few weeks ago, pump is the forced induction 255 walbro from autoperformanceengineering.com or something like that. The fuel pressure regulator is what seems to be the problem.

Alex

PS Randy, I know you probably meant well, but I really dislike Keyboard Warriors ;)
 
It's about time al35thsc

I been doin all this work trying to get the information for these questions. you started this thread. Mike knows his Chit huh well sometimes I can't get any good answers from him cause he is in to big a hurry or just plain don't care. I am not complaining . It seems like lots O dudes got something to say but it don't make sense. Hey what do you want for nothing. I have found out you have to keep hitting the board. You have to know answer yourself before you can post it for chat or disscusion. What is up with new members that ask a question then are gone. Don't mean to steal but I have started some threads that still arn't answerd.
 
Re: It's about time al35thsc

stocker 89 said:
I been doin all this work trying to get the information for these questions. you started this thread. Mike knows his Chit huh well sometimes I can't get any good answers from him cause he is in to big a hurry or just plain don't care. I am not complaining . It seems like lots O dudes got something to say but it don't make sense. Hey what do you want for nothing. I have found out you have to keep hitting the board. You have to know answer yourself before you can post it for chat or disscusion. What is up with new members that ask a question then are gone. Don't mean to steal but I have started some threads that still arn't answerd.

:confused: I also asked the same question on about 4 other different boards that are T-Bird and non T-Bird related, so don't get your panties in a bunch :D I dont sit in front of the computer on weekends and just got a chance to check it out here at work today.

Alex
 
Finally had time to look up some numbers.


1. Fuel system pressure with key on,engine off..........35 to 45 psi

2. Fuel system pressure (at idle)
A.FPR vacuum hose attached.......................................30 to 45 psi
B.FPR vacuum hose detached.......................................40 to 50 psi

3. At schrader valve.
A. fuel system hold pressure (after 5 minutes)...........30 to 40 psi

4. Fuel pump pressure (maximum)..............................65 psi

Injector resistance......................................................13.5 to 19 ohms

vacuum guage should be 20 .if not put hose clamps on every vacuum
line yuo can reach.use plastic ties on smaller vacuum lines,like the one
on the side or back of the intake maifold intake plenum.Do the PCV valve
to every splice.

When you take the FPR vacuum line off if it has gas in it the FPR may be bad.


Stocker 89 , You put the fuel guage under the hood because thats where
you do any adjustments.You can't read the pressure if you are working by
yourself,if the guage is inside of the car.

Hope this helps both of you.Randy
 
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Randy

It does help and I appreciate it. I didn't think and know it could very so much. Just one more experience I am looking foward to.
 
i get best luck with my pressure set at 48psi static. It ran the best at the track like that. I just bought 42lb injectors to replace my maxed out 30's....so now to get the same flow..i shouldn't need to run that high of a pressure.
 
Randy & Connie said:
Finally had time to look up some numbers.


1. Fuel system pressure with key on,engine off..........35 to 45 psi

2. Fuel system pressure (at idle)
A.FPR vacuum hose attached.......................................30 to 45 psi
B.FPR vacuum hose detached.......................................40 to 50 psi

3. At schrader valve.
A. fuel system hold pressure (after 5 minutes)...........30 to 40 psi

4. Fuel pump pressure (maximum)..............................65 psi

Injector resistance......................................................13.5 to 19 ohms

vacuum guage should be 20 .if not put hose clamps on every vacuum
line yuo can reach.use plastic ties on smaller vacuum lines,like the one
on the side or back of the intake maifold intake plenum.Do the PCV valve
to every splice.

When you take the FPR vacuum line off if it has gas in it the FPR may be bad.


Stocker 89 , You put the fuel guage under the hood because thats where
you do any adjustments.You can't read the pressure if you are working by
yourself,if the guage is inside of the car.

Hope this helps both of you.Randy

Much obliged sir. Still going to check the regulator tho.

For the rest of you guys setting your own fuel pressure, is this with an adjustable fuel pressure regulator???

Alex
 
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