Cleaned HFCM, now losing FP

[6speedsd]

Can I just loop the return ports with a single hose, instead of plugging each side individually, or would that cause some sort of issue internally with pressure somehow? (That may be an ignorant question)

What kind of pressure is typically on the return line? It's not much is it? Trying to decide if I can just run some 5/16 rubber fuel line with clamps on either end, or if there is enough pressure to justify quick connects and AN fittings. This all being done if the leaking supply line isn't the issue....


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[6.0 Tech]

I dont see why you couldnt loop them when you bypass them. Ford is very vauge on the description and operation of the pump, sorry i couldnt be of more help on that matter.

 

[6speedsd]

Well gents, I'm about a 6 pack away from striking a match and having an insurance claim!

New supply line from pump to factory hard line to the upper filter....no change. Looped the return ports together on the HFCM, and ran a separate line from the return off my regulator to the hard line tank side of the HFCM. No change. So basically, I've ruled out the tank, HFCM, supply and return lines south of the upper filter.

I'm getting 12.5v at the plug on the pump with the truck running. Replaced the O-rings where the stock feed lines leave the upper filter headed to the heads just for the hell of it.

At idle, gauge fluctuates about 3psi up and down, as it always has. It's drive able now at least, but anything over half throttle and it drops into the low 40's fast. I stood on it once, and it dropped immediately into the 30's...truck never missed a beat though...no sputter or miss or anything.

At my regulator, the line coming off the back of the drivers head has this sort of pulse when you hold the line. You can feel it, consistent and repetitive, but only on that line. I don't know if this is a clue, or if it's just sitting on the motor somewhere and causing it.

I really don't know where to go now. I did the bubble test at the upper filter housing when this issue all started, and got no bubbles. Part of me wonders about a bad oring on the injector, but I have no idea how to even test that without pulling injectors. Seems to me if that were the cause, I'd get some sort of running issues.


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[swinky]

Try a different gauge

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[swinky]

When was the last time the injectors were pulled?

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[6speedsd]

Did that too...ran a separate gauge in the cab with me, with the same results.

Injectors haven't been pulled since initially installed, around last November...15,000ish miles on them. I had issues win the regulator that came with my RR...kept sticking wide open and spiking the pressure at 100+. I'm wondering if that excess in pressure weakened some of the O-rings....but that again would be the most insane coincidence for one to fail in relation to me just cleaning the HFCM....which is when this nightmare started.


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[dsberman94]

Have you put a gauge directly off the hfcm? Wondering if you knocked some crap loose when you cleaned.

 

[swinky]

Copper washer might be bad and sending cylinder pressure in to the system

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[6speedsd]

Copper washer might be bad and sending cylinder pressure in to the system

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Shouldn't that cause a failed bubble test though?


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[6.0 Tech]

Yes that should caus the bubble test to fail. It may be that the hfcm is bad, and unable to supply enough volume to hold pressure. However, it could still be one of the white orings failing or a black ne if your oil is getting overfilled at all. Especially with the information that in the past you were over 100 psi. I have heard the orings will fail above 75 or so psi.

 

[6speedsd]

Oil has no diesel smell, is not diluted, and at the proper level. So I doubt that's the case.

Bad HFCM not supplying enough volume..... 3 totally different ones, with 3 totally different pumps? I just find that incredibly hard to believe you know.

Thinking out loud here....
My RR is just a bare bones setup. Lines off the back of the heads to a regulator, return line off the regulator down to the factory return quick connect on the frame rail, return port on the filter housing is just capped. The factory regulator spring/assembly (actually it's the blue spring kit) in the filter housing is all still there. This never made a difference before all this started, but could it be causing some sort of issue now? Not really sure how, as it's designed to keep pressure up, but still...just happened to cross my mind.

I'm going to run a gauge off the factory test port on the filter housing and see if that pressure matches my other gauges(which are reading after its passed through the heads/injectors). Doubt it's going to tell me anything, as it should still show a pressure drop in the system. Like I mentioned before, I'm frustrated and trying every little dumb idea that pops though my head.


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[6.0 Tech]

If he factory regulator is still in place, does it have fuel flowing yhrough it? Ok could see an o ring failing on the brass seat and causing all sorts of goofy chit if the regulated return is depending on it to help build pressure.

 

[6speedsd]

I would imagine fuel.is still flowing through it. The filter housing is still being fed as if it were all stock. Supply line up to the factory hard line into the upper housing.

Not sure why the regulator would be relying on the factory regulator to help build pressure though. I might just pull that spring out and see what happens.

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[6.0 Tech]

Im lost now man, you can try that and see what happens. Maybe pull the air bleed out of the top too. Also pull the brass spring seat.

Mhave you tried upping the pressure on the regulator? Maybe kcking it up to 70 psi and see what happens. Just a thought.

 

[6speedsd]

I haven't yet, but have been considering it to see if there is a pattern in how low it'll drop. At least maybe that way it'll keep me out of the danger zone of dropping below 50psi.

Surely this isn't an issue with my Aeromotive regulator. I don't see how the spring could be compressing under load, causing it to not keep pressure up, but again, just tossing out any dumb idea that comes to mind. I guess I could always cap my lines off the back of the heads, put the return line back on at the filter housing and run it bypassing the RR and see what pressure does..... Not that I want to do that, but it may be another option.


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[6.0 Tech]

Not saying that the spring is compressing, maybe th o ring that sealsnthe seat to the housing is gone and its bypassing the factory regualtor to a point, causing your fluctuation at idle, and bypassing it more at higher demand causing the pressure drop. This is out of left field though, just thinking out loud...

 

[dsberman94]

Have you actually done any sort of a pressure test on the fuel system in the heads?

 

[6speedsd]

Not saying that the spring is compressing, maybe th o ring that sealsnthe seat to the housing is gone and its bypassing the factory regualtor to a point, causing your fluctuation at idle, and bypassing it more at higher demand causing the pressure drop. This is out of left field though, just thinking out loud...

Yea I see what you are saying. However, I don't think it's relying on the factory regulator setup to offset pressure. Like I said, it wasn't an issue before all this started. I guess one way to find out is to just remove the spring and seat and see what happens.

The spring I suggested compressing is the one in my Aeromotive regulator...not the factory one. Surely Aeromotive uses quality metal in their springs, and it hasnt weakened to that point already...

I'm going to drive it to work tomorrow...first time since before Thanksgiving! I'll bump the pressure up to 70 before I leave and see how she acts.


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[6.0 Tech]

Good luck man...

 

[6speedsd]

Bumped pressure up to 70. Seems to fluctuate worse now. However, a hard acceleration kept it above 50psi. Seems like the faster I drive, the more it bounces around. 55mph and the gauge is up and down 3-5psi. Speed up to 70 and set the cruise, and the gauge is bouncing around close to 10psi.

I really am starting to think I've got a leaking injector oring...

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