Isn't the regulator built into the filter? I have an '06 and it seemed to be the only thing there when I changed the filter last month. 290,000 miles and never changed.

The pre facelift has the regulator separate but I think usually comes together as a unit. I thought they might be interchangeable but looking at some pics the preface filter looks like it is smaller!

When I say "separate" I mean that it fits onto the filter. You'll have changed both with your 06.

We had 2001s they had the big filler with the FPR attached at the end (but they did come apart) i still have the FPR from wife's when i replaced. I was thinking of cutting it in half to determine exactly how it works and how it might be possible to malfunction In a way that would send extra gas. Theoretically something could go wrong with the spring/diaphragm that makes it take more pressure to open. Could restriction on the output to the left tank cause this?


–awr–

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According to the PO, he installed a Bosch 3.5 Bar (50 PSI) regulator with part number*13531436110, because he had a starting problem, with low pressure, IIRC. I asked why not replace FPR and filter as a whole assembly, and he just shrugged and said it was all that was needed (he was just saving money, prior to the upcoming car swap, I believe).

If the pressure is out of spec (which is 50 psi + 3, I think), then I'll replace both as an assembly (Hengst or Mann).

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new fuel prssure readings taken (same as with the old pump, 3 years ago)
 

Just came in after testing fuel pump pressure. Rained yesterday, and my rotator cuff injury made using my right arm impossible, until late in the day, so this is all I was able to do. Even so, I had to get the wife to press the accelerator (her first time behind the wheel of the X5).

Attachment 85130 today
Attachment 85131 here's results from 5-11-22

Absolutely identical, so where does the change from a smooth running, no misfires or stalls (but with lean fuel trims) engine three years ago (and as late as 2 weeks ago, before the fuel pump failed)), to the smooth running, no misfires (but with stumbles and semi-stalls, and rich fuel trims) engine come from?

Only the fuel pump was changed, but the fuel pressure test today shows that it is providing the SAME pressure as the old one did, before it died. Nothing else was touched (mechanically), and only the adaptations were reset. But, though I had reset adaptations on my X twice before, there were no drivability problems, afterwards.

Should I pull out the new fuel pump, inspect the triple hoses (which I never touched) and see if one or more isn't sbmerged in gasoline? That's the only possibility I see, that may be causing problems.

But, I'm in over my head in this situation.

Only difference is

The fuel pressure looks fine, your gauge is probably reading a few PSI low. If you wanted to do a good test for fuel delivery you need to test under load with gauge taped to the windshield but that's not going help explain why it's running rich now. Did you pull the regulator hose off the boot and check that ?? Why did the PO change the injectors?

It might be a good idea to play around with adding vacuum or pressure to the reg hose like I was saying and watch the fuel trims just to make sure about if rich is rich or rich is compensating for lean.

I forgot to pull the vacuum hose off of the F-connector, will do that next. No idea why the PO installed new injectors; he may have done it because he was trying to refurb it to the best he could, and he might've thought it was the right thing to do...or he found a set of Bremi's on sale, for cheap. Anyway, they've been running OK for me, including times I tested smooth running values.

I've thought of attaching my hand-held vacuum pump to the F-connector via a 3-way Tee and extra hose, thinking that it might chase the lean problem I had been having. It'd do the same to test for changing the new rich condition. I'll order a set of Tee connectors (every time I get a set, i'll use only one, and lose the remainder, always.

The handheld vacuum pump is perfect for that, especially if it has a gauge. Poor or cheap injectors can drive you nuts with inconsistent mixtures.

You don't need a tee connector, actually it won't work with a Tee, just pull the hose off, plug the boot side and put the vacuum pump on the hose.

You shouldn't need a new fuel pump seal either.

X5 stalled/set codes while being inspected!
 

Fuel pressure constant suggest FPR and fuel filler ok.

If vacuum pump on FPR vent would do anything so should running at idle.

Realtime O₂ values? (Trims are directly related but it's helpful to see).

If you still have the other MAF it does feel like MAF. Have you done the tap test?

Also: was the needle solid?

I recall fighting trims for a long time i put in cheap O₂ so i could get them fast and it seemed to work at first but then i had trim problems.

I ended up getting new Siemen MAF and Bosch O₂ and finally fixed. (just months before deer killed the poor car!)

Ps: i would still do the vac/psi test on the vent hose. Maybe wrong type of FPR that changes with vacuum.

Honestly i don't know how the injectors work properly without the vacuum feedback.

Back to O₂: compare bank one and two; are they very similar as they should be?

–awr–

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I have a proven good Siemens MAF, and good Bosch O2 sensors (low mileage) on the X, and all seem to be working correctly (refer to post #63, with pictures of my Torque Pro display, showing MAF, O2, and fuel trims).

The constant fuel pressure readings would indicate to me that there shouldn't be a supply problem, so why is there a momentary stumble/stall exiting hard turns, and lean fuel trims suddenly becoming rich fuel trims?

Makes no logical sense to me.

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