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Discussion Starter · #1 ·
Okay so before anyone gets totally wrapped around the axle, yes I have read EVERY thread (that I could find) on this and the sister forum regarding this in the past several hours.

Situation is simple.

2015 3.5 132K on odometer.
All timing components recently replaced, engine ran fantastic. No leaks, no problems.
Completed the G2 turbo swap and after being down the engine has a hard time starting at first, then rough idles, then smooths out. Has ZERO power, no possible way to drive it safely as it is so underpowered it is dangerous.
Throws P0087 code, which we all know is low rail pressure (fuel.)
Hook up the diagnostic computer, watch pressures.
“Desired” pressure is higher than “actual” rail pressure.
Replaced HPFP (yes it is OEM.) No change.
Showing 58 to 62 psi on the LPFP (in tank.) Which according to Ford is allegedly within spec.
Matter of fact, all diagnostic data according to computer is flawless…aside from of course, our friend…Rail pressure.
Checked fuel pump fuse and relay, all good. Replaced both. Same issue.
Truck has new OEM vacuum pump. Nearly all lines have been replaced with OEM.
Plugs, boots, coils (before anyone asks) are new OEM, properly gapped.
KAM reset, relearn procedures completed, nothing.
Does this on stock tune, 93 performance and 93 tow tunes. Just for the giggle factor, tried the canned SCT tunes, no difference. Have not had tune revised, because well I cannot, with it not running properly.
Aside from dropping the tank and replacing the LPFP, I am at a loss.
Worked perfectly before the turbo swap, now I am looking at a paperweight and am scratching my head.

Every thread I have read, references the HPFP as the culprit. Yet nobody has nailed down a specific “fix.”
I am open to suggestions. HPFP did nothing, same symptoms.

(Certain I have left something out, just ask)

Ready, set…go!
 

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There can be a bunch of air in the system. Have you tried priming the system multiple times?

Also did you take a look at the cam follower under the HPFP?
 

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I'm thinking if LPFP reads good and HPFP didn't fix it could there be a pinched line between the two somewhere? Where are you reading LPFP from?
 

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Discussion Starter · #4 ·
Yes, primed multiple times, let idle for 30+ minutes on multiple occasions to heat cycle...

And yes, the cam follower was also replaced.
 

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Discussion Starter · #5 ·
There is a PID for the LPFP, which based on other threads was not previously available on earlier years? No idea, but it shows up on my machine and changes with the position of the throttle...which makes a whole lot of "no sense" due to the fact that it should maintain a constant pressure, correct?
 

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Discussion Starter · #6 ·
Ordered a LPFP. When I drop the tank (which is unfortunately 3/4 full) I will trace lines and see what I see. Not sure that there would be an issue considering nothing was done anywhere near them, but who knows, maybe something happened I missed. Frustrating.
 

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I'd try to mechanically measure it just before the HPFP, assuming the HPFP and everything downstream is working as it should.
 

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Discussion Starter · #8 ·
Not a bad idea. I could piece together an adapter of sorts I believe to make that work.

It is just super odd that it popped up out of nowhere, first thought was tune, but never had an issue with the tunes before, plus it does it on stock tune as well.
 

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Well if it checks out before the hpfp then the issue may be further downstream. I guess you need to isolate whether there is any mechanical issue at all or if it's tune related.
 

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Discussion Starter · #10 ·
It behaves the same on all tunes, so I am pretty certain that is out of the equation. (Never know)

I had read where there is not a PID for LPFP pressure, yet my machine shows it in real time, which in itself was a bit odd.

The main concern is that the desired rail pressure and actual rail pressure were so drastically different. Sensor? Crap at this point I am just grasping at nice thoughts.
 

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LPFP is spec at 62-73 PSI for the 3.5L ecoboost.

Here is a procedure from Ford. Its a bit different but should give you an idea. However, they do use their own kit which T's in.
 

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Discussion Starter · #13 ·
the LPFP will be here Wednesday. Going to have to pump down that fuel tank so I can drop it. I believe it is 26 gallons as it is not the 36 gallon extended range model. So at 3/4 full its going to be one heavy dude
 

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Discussion Starter · #14 ·
Is there any tips or tricks to dropping the fuel tank on these trucks? I imagine it is just a typical setup, straps, filler neck, lines.

Planning on pumping out at least half of the remaining 20 or so gallons to reduce weight prior.
 

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Just to "spit ball", if your actual Fuel Rail Pressure is too low and it's not the HPFP, based on your other info, I doubt it's the LPFP.

It almost sounds like an injector could be stuck open. Have you checked the spark plugs to see if ANY appear to be wet with fuel?
 

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Discussion Starter · #16 ·
I read that thread last night and as a shot in the dark, pulled the plugs, all dry!

Not sure there is an "easy" fix to this one.

On another forum someone dropped their tank and pulled the pump finding the "filter" which I believe is just a sock completely clogged...they said this fixed the issue. We shall see...

Honestly just grasping at straws at this point.

Thanks for the suggestion, Grim
 

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2021 Powerboost Platinum FX4 Kodiak Brown
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Yes, primed multiple times, let idle for 30+ minutes on multiple occasions to heat cycle...

And yes, the cam follower was also replaced.
Is it impossible for the cam follower to be installed wrong? Or, can it only fit together correctly or not at all? I haven't ever swapped the HPFP, so I wouldn't know.

Sent from my SM-G988U using Tapatalk
 

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Discussion Starter · #18 ·
Yes, it has a "tongue and groove" type fitment. Slides in and out one way.
 

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Discussion Starter · #19 ·
Just traced fuel lines from tank all the way to motor. No kinks, not pinched, nothing.

I do wonder since the “fuel filter” is in the tank if it is clogged, considering how nasty the rest of the truck was.

And just for giggles, ran diagnostics on the injectors, operating as they should, aside from starving for that proper rail pressure.

Going to pickup a transfer pump to empty the tank now.

In the back of my mind I’m finding myself wondering “what will be wrong next?”


Tapatalk - it’s like bacon, for your phone.
 

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2021 Powerboost Platinum FX4 Kodiak Brown
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I gotta say though that you keep a good balanced attitude about the whole thing. Maybe you really are throwing wrenches against the wall and cussing a blue streak, and then calmly posting here, , but I bet not.

Sent from my SM-G988U using Tapatalk
 
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