Low Fuel Pressure at WOT

Since you have a 2005, does the HFCM have the fuel heater (early 2005)? If so, was the cover ever removed and the area cleaned?

Stock, is a regulated return. LOL.

BE, I should have waited for the videos to be viewable. Good work.

When you are deadheading one of these, it should go up to ~100psi. That is where the internal blow-off valve is set within the removable pump. When I had a blockage, it got that high and screamed like a pig. So that's one oddity.

The reason I asked about the fuel heater is I have a video in waiting for when I can do the narrative. My voice has been screwed since July when I got Covid due to fungal nasal issues. But the video is the forensics on two HFCMs that members of FTE sent me, which failed to pump. Both had running motors. The spoiler of the video is one was blocked in the heating chamber from all the fuel debris off the heater. The other was blocked by debris in the HFCM nipples. The truck probably had a bad case of organics, the primary filter failed, and debris was everywhere. Including on the face of the 100psi blow-off valve. This then may have allowed the valve to leak all the time to some degree, and you could never get the full 60-65psi, or if it were a small leak, you would get below the normal 52-55psi the majority of us see when we go PTF.

When I used my HFCM to pump out my tank for removal and looped the return, it showed air/foam for longer than I expected. I don't know how long you pumped like that with the loop to check for air. Unfortunately, I did not video much of doing it - I didn't think there was any relevancy at the time.

Curious what is going on there.

TooManyToys said:

Stock, is a regulated return. LOL.

BE, I should have waited for the videos to be viewable. Good work.

When you are deadheading one of these, it should go up to ~100psi. That is where the internal blow-off valve is set within the removable pump. When I had a blockage, it got that high and screamed like a pig. So that's one oddity.

The reason I asked about the fuel heater is I have a video in waiting for when I can do the narrative. My voice has been screwed since July when I got Covid due to fungal nasal issues. But the video is the forensics on two HFCMs that members of FTE sent me, which failed to pump. Both had running motors. The spoiler of the video is one was blocked in the heating chamber from all the fuel debris off the heater. The other was blocked by debris in the HFCM nipples. The truck probably had a bad case of organics, the primary filter failed, and debris was everywhere. Including on the face of the 100psi blow-off valve. This then may have allowed the valve to leak all the time to some degree, and you could never get the full 60-65psi, or if it were a small leak, you would get below the normal 52-55psi the majority of us see when we go PTF.

When I used my HFCM to pump out my tank for removal and looped the return, it showed air/foam for longer than I expected. I don't know how long you pumped like that with the loop to check for air. Unfortunately, I did not video much of doing it - I didn't think there was any relevancy at the time.

Curious what is going on there.

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Sounds intriguing. I look forward to seeing that video, though I hope I can get my rig fixed before that...

I ran the pump like that for at least 2, maybe 3 full key cycles (pump runs for 20 seconds, right?) before I took the video. The first cycle was just barely enough to get prime the module and get a bit of fuel out the outlet. The majority of the air cleared up pretty quickly after that.

So, since I'm only getting 70psi, would you say my pump is probably bad? Or perhaps the blow-off valve? I'm curious if maybe the pump is weak, and while it builds moderately decent pressure, it's not able to flow enough to keep up with the demand of a WOT run. I wouldn't rule out the possibility of it sucking air in somewhere between the tank and the HFCM, but judging by the fairly small amount of air coming through, I doubt it would be enough to cause the problems I'm having. Am I making any sense here at all?

Just for the record, the truck was running just fine, the only symptom was the low pressure on the gauge. Also, the tank is right at half full (minus however much I've pumped out into the can, lol)

It's late -if this makes sense.

For you to have more than the normal 10psi drop from idle to WOT with this system says there is a volume issue. So it's either delivery to the HFCM, or an output issue. The regulated output can be less due to leaks around the pressure regulator seal, the air bleed orifice at the top of the secondary filter, the blow-off valve leaking, or electric motor deficiency.

Voltage should be near battery voltage (whatever that is) when the key is on. Otherwise, there is resistance in the circuit cause low power. While you are doing your key-on checks, unbolt the alternator lead off the passenger battery positive. That also feeds the GPCM, which will pull down the voltage when you check. The voltage should be checked at the pump connector while the motor runs.

The only way we mortals can check the tank supply, if everything else is good, is by using a remote tank/can as the tank, with both supply and return into the container if you going for a drive. The HFCM will pump the 5g container (or whatever) into the tank if the return still goes to the tank. If it's still more than a ~10psi drop under WOT, then we are at the fuel pump. And those are replaceable only. I just destroyed two good (one relatively good) fuel pumps doing the full forensics, unfortunately, or I'd send one to you.

Just for a data point, when I pumped at no pressure, it required 2.7a, and at 65psi 5.3a, off a fully charged Group 65 battery.

Stills from the video of the two different HFCM failures.

SuperDave23 said:

Can you clarify the non-OEM kit you used? I'm wondering if you got a bad regulator valve or weak spring out of the box? The OEM kit isn't very much might be worth a try?

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If I remember right, it was this one from XDP. I bought it quite a while ago, but only installed it last year (not brilliant, I know...).
I'm slowly learning my lesson on which parts are ok to go aftermarket, and which ones to go OEM.

I'm waiting to hear back from my brother on a price for a Ford kit. Nice to have a brother who works for a Ford dealer!

I'm thinking about pulling the regulator back off and checking the seals and such. Not much I can tell on the spring itself, but this doesn't seem to be a pressure issue directly, rather a flow issue that manifests itself as a pressure drop under load. My only hesitation about condemning the regulator is that I know the pump is only outputting 70psi, both on the bench and in the truck (I tested the output pressure this morning with the inlet hooked back up to the tank).

Allow me to think out loud for a minute. The blue spring is supposed to bring it up to the 60psi range, right? So if my pump pressure is 10psi higher than that, but my regulated pressure is right around 60, then that should tell me that the regulator is doing its job properly. The fact that the pump is only at 70 makes me think the pump is weak. If it's not able to make 100psi, will it be able to keep up with the flow demand at WOT? My gut is telling me I have a weak pump, but I'd sure like to verify that before I spend the money on it. I don't mind spending money, but I hate wasting it.

bismic said:

From my contact with Parker:

Good morning. I am the pump product manager at Parker Racor and spent many years working on the 6.0L Ford Fuel System. ​

​

The Ford 6.0L fuel system is set in the mid 50 PSI range I believe. The pump when running at alternator voltage will produce around 110 LPH (29 GPH) at 60 PSI outlet restriction. ​

So when the pump is installed on the vehicle the flow could be as high 32-35 GPH when the filter on the frame rail is clean. As the frame rail filter starts to choke the flow may drop 2-3 GPH. ​

​

Please let me know if you have any specific other specific questions about this pump. ​

​

Thank you ​

xxxxxx​

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Thanks for these specs. Maybe I'll try to rig up a jug to the return line from the secondary filter and time it to get a rough idea what the flow rate is.

Thanks for posting that, Mark.

The regulator at the secondary filter has nothing to do when you deadhead the system. Over the 55 to 65 psi range of the regulator at the engine, it will open more when deadheaded to try to get down to the stated pressure. Then the blow-off 100 psi regulator in the pump will be the dominant control.

Even if the flow input were restricted, it would only take seconds longer for the pump to reach 100psi when deadheaded; there is no volume or flow; it's all pressure generation. It should be at 100psi. When you are in a bypassing loop, flow or volume matters.

In-pump relief valve.



Debris on the valve that can keep it open, causing a lower pressure when at injector full demand.







So I think either your pressure gauge is off, you have resistance in the circuit feeding the pump (voltage / current low), or the electric motor is damaged. Unless someone else has another view. Being an R&D guy, I always expect to be 80% wrong.

I think he has been through all that.

Bad tanks of fuel, for color commentary.

To the right of the o-ring should be clean fuel. Failed primary filter.

jokester00 said:

Has your fuel pressure always been this way or did it just start? Or...did you just start monitoring fuel pressure and that's what brought it to your attention?
-jokester

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A little of both. I did just start monitoring fuel pressure a few months ago. (Another one of those "bought the parts, never installed them" situations.) However, I'm pretty sure it wasn't doing this when I first got the gauge. And it may be my paranoia, but it seems to have gotten a little worse since I first noticed it.

TooManyToys said:

Bad tanks of fuel, for color commentary.

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Woah, that's disgusting. I just pulled mine apart for grins and giggles, and it's not at all dirty. Maybe a small amount of debris, but some of that may have fallen in as I was taking it apart. Here's a few pics.


So, I've pretty much decided to go ahead and throw a pump in it. I suppose I can't be 100% sure that's it, but every test so far has pointed me in that direction. Next question: you mentioned in your HFCM video that Racor sells their HFCM to Carter and Napa. I see on RockAuto I can get a Carter pump (just the pump) for $61.89. Does the same go for the pumps, or do I need to try to find a Racor pump? Looks like they're up to around $200 now.

Wow the OEM fuel pumps are close to $300. It wasn't that long ago that they were $120.

Racor: PFP58054

You can get it at DieselFiltersOnLine for about $290 and free shipping.

$280 at the Racorstore and who knows how much for shipping.

Jack has posted that the aftermarket brands are probably re-labeled racor, but hopefully he jumps in for himself on this topic!