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Topic: Fuel pressure question.... (Read 3836 times) previous topic - next topic

Fuel pressure question....

Reply #15 –
read up on the fuel pressure vinny,  I remember reading that the stock pressure at 39 psi is what the computer expects,  I also think the computer will trim the injector pulse to compensate for the higher pressure.  Your already fooling the EEC with doctored readings from the mass air meter.. messing with the FP is just going to throw it off more.
[SIGPIC][/SIGPIC]

Fuel pressure question....

Reply #16 –
I want to keep the pressure that the computer wants.....I also want the pressure to be what it needs to be. I'm not trying to turn it up high and get crazy. I just want it to work as it needs to. I've been thinking that the engine may not be getting the fuel it needs.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Fuel pressure question....

Reply #17 –
At 22 lbs at the rail it most definitely is not getting enough FUEL. I cant believe it even runs correctly. Question is your gauge accurate???
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Fuel pressure question....

Reply #18 –
I can only hope that it's accurate. The gauge is brand new (and yes, I know that doesn't mean that it works right.). The car runs fine, but feels weak when you hit the skinny pedal. I have felt a little low end struggle. At times, strong. Other times....not so much. I've questioned a fuel issue for a while. I'll swap the filter first, and see if that helps. Wondering if I need a pump the more I think about it. Filter first, though. First thing in the morning.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Fuel pressure question....

Reply #19 –
Yea 22 pounds is way low it would run like a dog

Fuel pressure question....

Reply #20 –
Going to grab a filter shortly.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Fuel pressure question....

Reply #21 –
do what i do to check the fuel pump,, works real well with an aod tranny and im sure the same on a stick.

buy the extender hose on your fuel presure tester
duct tape the guage to the windshield with the tester connected
drive the car and observe the guage

as the rpms go upwards in between gears, the fuel presure reading will decrease
you need to take a mental note of where it averaged out at with respect to the very lowest reading which will likely be between first and second gear.

22 is the absolute worse case reading you should ever see at the highest RPM while the car is in between 1st and 2nd,, testing the fuel presure under a load like i describe is the absolute best way to verify your fuel pumps capability to deliver the demand.

there is a **HUGE*** difference in a car at idle vs under load,, many people see good or within specs readings "at idle",,, yet thier comlaints are usually describe what they feel while they are driving, so why not find out what is going on with the fuel pump "while your driving".

hopefully you wil find out real numbers instead of misleading "at idle" readings in order to determine the right next step.

didnt you revert back to HO speed density?

Fuel pressure question....

Reply #22 –
and dont forget the obvious...

check the voltage you have going to the pump such as at the pump side of the fuel pump relay.
the relay on most of our cars brings power from the battery to the relay on a yellow wire.
When the relay is triggered, power is sent out to the pump on the "next big wire" or what my records show as the pink and black.
measure the actual voltage you have at the pink black wire which is the fuel pump power feed.

if your idle voltage is 14.x volts at the alternator output and your reading at the fuel pump relay pink black wire is 11.xx, then you may just have a low voltage problem and the pump is going to spin a little slower.

relay input on yellow wire > if it reads like 13.9v and then the pink black fuel pump wire has like 11.x then the relay contacts are dirty or burnt up and the relay is the fault.
the voltage reading is important.,, it travels a very great distance across the lenght of the car to finally make it to the fuel pump.

to fix this, if it is low, we can discuss that later,, im not trying to ask you to spin your wheels or anything, just mentioning something that people tend to forget.

you can temporary bypass the circuit and feed 12v onto the pink black wire (fused for safety) from the battery and see if the engine feels any different.

Fuel pressure question....

Reply #23 –
I installed the H.O cam, but left the Mass Air. The car idles great, cruises well, but under WOT, seems a bit lacking. I have thought for a couple of weeks that it was a fuel issue. I just picked up the filter and will install it in a little while.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Fuel pressure question....

Reply #24 –
LOL, delete your fuel injector screens,, will be the best mod you've ever done!

Fuel pressure question....

Reply #25 –
I've actually heard that before, but, I'd be afraid of  getting in the injectors and killing them. I may be over thinking that. When I did the last intake swap a while back, the injectors looked great. I'll check them again when I install the FPR.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Fuel pressure question....

Reply #26 –
Quote from: vinnietbird;419180
With the current FPR it was reading about 22 at idle with the vacuum hose hooked up.

 
Quote from: TOM Renzo;419184
Haystacks is correct most all injectors are rated at 43.5 PSI for  flow at rated output. And an injector should never be operated past 80% DC. I would set the regulator at or around 44 LBS NO VACUUM. 22 lbs is ABSOLUTELY NG even for a stock setup. Better find out why your fuel pressure is so low before jumping in to new injectors or a regulator. Your car must run terrible if this is the fuel pressure you are running. And you could very well have leaned the motor out drastically. Better check that out real fast. Good luck


Vinnie check the fuel pressure with the vacuum line off. As Tom said it should be around 40 PSI at idle (37-42 is within specs) with no vacuum. I think people got confused and thought you had 22 PSI with the vacuum line off the FPR.

As others have mentioned the EEC will tune out increases in fuel pressure from an adjustable FPR. I'm running a stock replacement Motorcraft FPR on my Thunderbird and it works fine.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

Fuel pressure question....

Reply #27 –
At idle....34 with the vacuum, and 42 without. That's with a Ford FPR. I had 22 or so when I got gas yesterday (vacuum on). Maybe the fuel pump is doing well.....then not doing well.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Fuel pressure question....

Reply #28 –
34 and 42 is right but 22 is bad lol

Fuel pressure question....

Reply #29 –
Haven't had time to test drive it. I will tomorrow.  I'll probably go start it up later this evening and see if the numbers stay the same. I'm having a gut feeling that the pump isn't being consistent.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..