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Are you sure your pressure reading is accurate? I would test it if you haven't already. Finding an accurate pressure gauge takes a little time from my experience and I think that is also true (perhaps to a lessor degree) of the electronic sensor/gauge combinations.
Other than it showing in the range of what it seems many are seeing...not positive it’s accurate. My gauge is in the test port of the upper filter bowl, I assume that’s the best location since it’s after the regulator and what the injectors are actually receiving?
I just saw a Dieseltech Ron video (RIP) where he stated that fuel pressure needs to be above 40psi to keep the injectors safe. And during his test the pressure was 50psi driving around but only dropped to 45 under full throttle. So now I’m even more confused.
Also, his gauge was tapped into the top of the upper filter cap. Would that show different pressure than the test port? He did mention the test port is what Ford recommends but didn’t mention whether there would be a pressure difference.
The test port location is the best location for measuring pressure, but I see no issue with having it on the secondary fuel filter cap. It will be a little lower there, but I wouldn't expect it to be more than 1 or 2 psi lower - at least under normal conditions. Ford states that 45 psig is minimum, but I like to see above 50 psig because I have seen frequent issues with pressure gauges "drifting" on accuracy.
I was fortunate enough to have access to pressure calibration and test equipment at work, so I saw the variability in accuracy quite a bit with instrumentation at work. Because of that I have a very accurate manual gauge that I can check my other gauges against. Periodically I see some of them drift off of calibration. I am not wanting to get into another "debate" over it, but I have a few "stick" gauges for tire pressure that are accurate (found 1 or 2 that weren't so accurate also) and are useful for a quick validation of the electronic fuel pressure (and degas pressure) gauge (I did identify a bad electronic gauge this way).
I think most of the time, when people talk about their lowest reading, I tend to believe it's around 52 psi. From what I remember, with the test port off the filter cap without a blue spring upgrade, I ran warmed up around 56 psi and WOT down to 50-52psi. The spring should not be the factor in the lowest pressure. It's trying to maintain the 55-65psi range. But if the volume isn't there, or excessive fuel is bypassing the plunger seal, seat ('03), or air bleed orifice, the pump can have a hard time keeping up, just as the fuel pickup can be at fault.
In hindsight, It might not hurt to revisit the plunger first.
Bismic (Mark?)- yeah, I’d prefer to see it stay over 50 as well. Is there a gauge you’d recommend? I have no idea and would sort of be in the same situation if I just bought whatever.
TMT Jack- the plunger that is part of the blue spring kit? So, even if the spring is doing it’s part the rubber seal around the plunger may be giving up pressure?
Also, what do y’all think about being tuned having an effect on pressure?
Me, I keep waking during the night, and at this age, 6.5 hours seems to be about it.
A very aggressive tune and injectors that use more fuel than the original design parameters can impact WOT pressure. The original design does not have a lot of volume margin, and if it did, we wouldn't see any pressure drop. The design is a loop of constant volume, regulated pressure. What fuel is used by the injectors is bypassed off the loop. If you bleed enough volume off, pressure drops. But if there are any issues of delivery or loss, the pressure drop is higher.
I covered this in my video about the HFCM.
Yes, the spring can be fine, the seal can be the issue, and we've seen a lot of that with any of the replacement kits, including Motorcraft, although the Motorcraft is the most reliable for spring and plunger. And for the early trucks, you can't forget about the o-ring behind the replaceable seats.
Me, I keep waking during the night, and at this age, 6.5 hours seems to be about it.
A very aggressive tune and injectors that use more fuel than the original design parameters can impact WOT pressure. The original design does not have a lot of volume margin, and if it did, we wouldn't see any pressure drop. The design is a loop of constant volume, regulated pressure. What fuel is used by the injectors is bypassed off the loop. If you bleed enough volume off, pressure drops. But if there are any issues of delivery or loss, the pressure drop is higher.
I covered this in my video about the HFCM.
Yes, the spring can be fine, the seal can be the issue, and we've seen a lot of that with any of the replacement kits, including Motorcraft, although the Motorcraft is the most reliable for spring and plunger. And for the early trucks, you can't forget about the o-ring behind the replaceable seats.
Got it...sooooo, new blue spring kit. Suh-WEET!
Will let y’all know the results once I get time to install it!
Could I have a link to your HFCM video?
And I hear ya...I wake up to go to the gym around 5am during the week. So guess what time I wake up on weekends...even if I go to bed late... 🤦♂️
Also, with regards to the little white plastic “orifice” in the blue spring kit...what purpose does that serve? Bleed any air at the top of the fuel bowl?
Hmm...apparently I have some debris at the valve where the filter seats, because if I have a full tank it keeps draining forever. I’m guessing that requires HFCM removal to clean?
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