Did a search and came up empty handed. Anyone know what the fuel pump discharge pressure prior to the filter is supposed to be as well as the rail pressure? My pump sounds kind of weak, even after the filter change but I don't want to drop $400 for no reason. If I had a tuner I could see the rail pressure but i'll probably just hook a gauge prior to the filter if anyone know what it's supposed to be.

 

Sounds weak huh.....define sounding weak. Are you having any driveability problems?

I should be able to get you a number though, check back after 4:30ish....

 

When I turn the key over and the pump primes, it's not a loud whining sound like it used to be. It's more like a slow oscillating sound. The only time i'm having problems is when my truck is warmed up and I go WOT, it spits and sputters. I changed the filter the other day and same problem. I just don't want to go into the plugs/coils if it is fuel related.

 

Gotcha.

KOEO-35-45 PSI
KOER-28-45 PSI

 

Thanks, but what does the KOEO & KOER mean?

 

koeo = key on / engine off
koer = key on / engine running

 

Thanks alot guys.

 

Have an 06' F150 5.4L Triton with low fuel pressure

starting engine fuel pressure 40-60psi
engine running fuel pressure 20-30psi
(increases to 30psi when accelerating)

-changed fuel filter
-changed fuel pump
-changed fuel pressure sensor
-changed fuel pump voltage regulator
-no air/vacuum leaks
-no codes
-reseated fuel system wiring connection beneath drivers door

Help, Ideas?

 

Fuel pump voltage regulator? Do you mean the FPDM?

 

Yes I mean the FPDM, (fuel pump driver module).
Don't have any restrictions in the fuel lines.
Vehicle starts and runs, but runs rough and bogs down
under any acceleration.

 

Your fuel pressures look like there within tolerance. What's your battery voltage when running? The fact that you don't have any codes is strange. Maybe something is wrong with your throttle body. You could pull the air intake and check to make sure the butterfly on the throttle body is opening as expected when you romp on it. Sounds like its getting lots of fuel and no air if it is bogging down. If there was air and no fuel you would also bog but probably would get a lean code but maybe not, either way I would make sure the drive by wire throttle body is working before doing anything else, easy to eliminate it as a possible issue.

 

Thanks, I'll check the voltage and Throttle Body, will double check the codes too.
The fuel pressure is being monitored just past the fuel filter with an inline 'T'.
The pressure runs 20psi at idle and increases to ~30psi with acceleration. At start up it
jumps to 40-60psi.

 

The 06 I believe has a return line. In 08 there is no return line if I’m not mistaken. I’ve got an 08 F250 5.4, automatic, 4WD. I’m getting the same acceleration at 1/4 throttle as at WOT. No codes. No misses, nothing strange except loss of power. KOEO is 30psi, KOER is 30psi and with WOT the pressure drops to 20 psi then recovers. She idles smooth, will accelerate to 80 and hold speed no problem but the acceleration isn’t right. It feels like lean. I’m hoping you’ve got these specs before I replace the fuel pump.
Already replaced fuel filter, air filter, ran Techron through, pedal re-learn.
Thanks,

 

FPDM-equipped systems do not have a return. This is from 04 to present. You need to check your FPDM for corrosion on the back side.