And the rubber seal that goes on the brass plunger (or whatever it's called) looked very different from the old one. This is how it came in the bag.


I thought, maybe the forces acting on it over 4.5 years caused it to deform to the shape it's in today. And that's how Ford sent it, so I installed it. With outdoor temps of 60 degrees, my fuel pressure was 80 psi. I knew that couldn't be right, but I couldn't verify with a manual pressure gauge, because my schrader adapter couldn't be found. Over the course of last week, the pressure slowly dropped as outdoor temps went up. This morning it was 80 degrees and pressure was reading 71 psi. So it seemed to be working normally, but still the pressure was higher than I've ever seen with just a new blue spring.

I took a closer look at the old plunger and found something I never knew. The underside of the flange has a bevel undercut, for the conical side of the seal to mate with, it would appear.



I flipped the seal around, put everything back together, and now FP is reading 62 @ 87 degrees ambient temp. I am hoping the fresh spring and seal will keep FP from dropping more than a couple points at WOT. Lately its been dropping at least twice that much.

 

Moving on to part 2 of my upper fuel bowl fun.

When I pulled the filter for the blue spring install, I noticed something else I'd never seen before:


Isn't there supposed to be a fat green o-ring at the top of the stand pipe? Of course there is:


I have zero idea when or how this happened. It's possible it's been broken since I bought the truck, now over 4.5 years ago.


Is it just me, or does this look like a part that was intentionally designed to break? In the course of a week, I have had to replace the fuel filter stand pipe AND the oil filter stand pipe due to broken plastic parts. WTH?

 

I found the same issue this past winter, new Motorcraft spring and valve kit.

When first installed it was 80 psi for a moment or so, and slowly dropped to 75/76 psi over about an hour.

After approx 300 miles, FP dropped from 75 psi to 66/67 @ idle on start. No other indication, just dropped on start one day.

When I removed the new FP relief valve after seeing the pressure drop, the new style seal was slightly deformed. It went back into shape pretty quick, I couldn’t get a picture of the deformation, but you can slightly see it in the pic.

I don’t know if it can hang up slightly on that seal, or the new larger diameter is enough to slightly hang up. I think it may be possible for the new seal to slightly hang up on the bore ribs into the fuel bowl, but I have to look / measure to confirm.

I tired the original FP relieve valve, with the new blue spring, it showed 66 psi @ idle.

I picked up a second new Motorcraft blue spring kit, same measurements and seal.

I had it in and out several times, different configurations of old valve new seal, new seal old valve, etc etc. (Edit, I looked up the maintenance log, I did not swap / change seals or open the new second kit. I was going by memory, and thought I did. I had only ordered the new kit when I was doing this).


On final install it would start @74 psi, and slowly dropped to to 71/72 psi @ idle, using the first new Motorcraft blue spring kit relief valve and updated seal. I left off there with it.

The last time I used it, it was sitting around 71 psi on start @ idle, drops to mid 60’s (63/64 iirc) under heavy throttle, but haven’t used it much at all the past few months.

I’ll be back into it again soon, I’d like to take the time to look at it closer.


Pics:

The new Motorcraft relief valve has a new style seal, and is a slightly larger diameter. (Both new Motorcraft kits measured the same)

Original FP relief valve: 0.300”
New FP relief valve: 0.03025”


The spring in the pics is an old spring.




Seal deformed when removed, it was a bit more than this but rebounded back before I could get a pic. The dirt on it is something from me handling it.

 

Did you try flipping the seal around for any of your trials?

With the seal in the "as shipped" orientation, it makes sense that the FP would be higher due to the greater width putting more pressure on the spring, which in turn would cause more deformation of the seal, especially the way it tapers down towards the bushing in the housing. Which may explain why the pressure drops over the course of a day or two. I suspect that if it stays that way it will fail prematurely due to the higher amount of deformation. I really think it's supposed to go the other way around. It looks like BPD agrees:




https://bulletproofdiesel.com/collec...or-kit-6000084

 

Thanks for the heads up on this

 

I don’t think so, no. It’s was a few months ago, I can’t remember what ways I did it now, now I’m questioning if I even swapped seals around from valve to valve. I really don’t remember. I edited my post above on that.

EDIT: I keep a maintenance log for the truck, the notes are in there. No, I did not swap seals around.


435 miles since new blue spring install.
New injectors at time of new blue spring kit.
PPT Remans. Stock.
(Edit) New alliant HFCM / pump.
2006 F250. 115k total miles.


I just took it out this afternoon to try a few wot runs. First time I’ve been able to since instal.


Engine was warmed up for an hour with the block heater. 42*F ambient.

On start, 70 - 72.5 psi @ idle. It was bouncing all over between.

Reving up to 12/1500 rpm, truck static, fuel pressure would stabilize around - 71.5 psi.

Normal driving / moderate throttle input accelerating on level ground - 67 - 69 psi.

Uphills normal driving - 66 - 67 psi.


WOT runs. Short runs, momentary 2-4 seconds, 30 - 50 mph. Most would dip to 57 - 59 psi.

One run it dropped to 50.7 psi momentarily, uphill run.


Not sure what to make of it. I did not like seeing 50 psi on new injectors.

 

Fuel sloshing in the tank.

 

Ok, took me a bit to refresh my memory, re read my Mtce logs, dig out the old and new parts, and get back up to speed where I left off.

My apologies, I was doing this back in Jan / Feb.

To be clear, I was mistaken in my earlier post, NO I did not swap or reorient the seals at all, I have no record of it. I tried the new as it was, the old valve with new spring, and back to the new valve with new spring, and removed it a couple of times to ensue it was clean and not hanging up on foreign material. Once I did find something small, but noted it was probably not enough to hang it up. I did not open the new Motorcraft kit either, I had only ordered it at the time so I could look at it in the future (as in now).


I just opened up the new Motorcraft blue spring kit. Fuzz, it appears you and I received kits with the seals installed backwards. I wonder how many others are out there like that? To me it looked like a new update, I didn’t know other wise. Both kits I purchased were from my local dealer.

The new kit has the seals installed the other way, and it looks the same as the original. I have not measured the diameter.

I’ll swap the seal around tonight / tomorrow and see what difference it makes and report back.

New on LH, original on RH.

 

At least you can look at your logs and figure out what you did. Mine are not nearly that detailed.

That seems to be the million dollar question. The other is "How many people know the difference?"

Looking forward to your results. I too would not be happy with 50 psi after all that money and effort.

 

I just swapped it around. I took video of the fuel press guage before and after reorienting the seal. I’ll try to post them up on YouTube later and post the links.

It would appear to me that the seal was installed backwards, and shipped out like that.

The only change I made was the seal, nothing else. Removed, and reinstalled correctly.


KOEO: 61 - 62 psi, bleeding air out of the system.

Running: Idle after a minute or two 61.5 - 62 psi and fairly steady.

Normal driving 60 - 62.5 psi.

moderate throttle 60 - 61 psi

and up hills 60 - 61 psi.

WOT runs. 56.0 momentarily was the lowest I saw, would stay around in the 56.5 - 57.5 psi range for the most part on wot, momentarily.

I still would have hoped for a little better. 60 or better at min WOT. Not that I use wot often.

I may try the other blue spring kit tomorrow, just to see if there is a difference. I wonder how many are out there like this too? It simply looked like an updated seal of some type, I actually thought about making a thread at the time, but decided to deal with it in the spring. Here we are, your thread was good timing.

We’re playing with fire here, just think if you didnt have a FP guage to see…. And I wasn’t able to do WOT runs in the winter.


Pics.

Before.


Seal reoriented.

 

I have a feeling that Ford has a new vendor with these.

Pressure drop at WOT is not a factor of the fuel pressure regulator. This is a constant-volume, regulated-pressure supply system. When pressure drops under high fuel injector output, it's an issue of the volume of fuel pumped.

 

Understood. But, As long as the pump will keep up, in theory a higher rated spring should raise the entire FP range, no? If the pump won’t keep up, then that’s a different story. I would hope a new pump would keep up.

 

Prescription steroid cream for the prosiasis (or eczema) under the thumb nail. It is a pain in the *** to get rid of, but it is doable.

 

Yes, the spring controls pressure, and a stiffer spring raises pressure. But only while volume meets demand. It’s well known that this fuel system is volume-limited, and it's not uncommon to see a WOT drop pressure to about 55 psi, maybe 52.

 

I think we’re both saying the same thing. I should clarify, I’m wondering if it’s possible being installed incorrectly with the spring being compressed too much (higher pressures) and then heat cycled several times, it may have lost some, even slightly, some of its tension. The new kit spring may bring it up slightly across the range. Just slightly.

For a small amount of work, it probably worth checking. Maybe I’ll get lucky.