Ok - swapped out what I'm going to call HPFP #2 (the junker, which was the second one to come into my possession) for HPFP #1 (the one put in the car in 2013 under the car's first owner).

HPFP #1 was in the car when I bought it last year and it was malfunctioning when I bought the car. Today I traded out the some-flavor-of-Viton original o-rings on its solenoid for new fluorosilicone ones, popped it into the car, did some warmup testing and took it for a spin.

Similarities to HPFP #2+fluorosilicone rings: clean first startup. Pretty clear signs of wanting to warm up before going to normal PSI ranges.
Initially temperamental about getting to proper PSI, to the point where I gave up, decided to stop the engine, then start it and just take off before it got a chance to "decide it wasn't working." Bingo, normal-range PSI.

Differences: HPFP #1 feels a little more stubborn than HPFP #2 but that sense is fully subjective. Might also be because it went so long operating solely in limp mode that it may just need some shakeout.

Once I got HPFP #1 it to normal range it stayed there through some engine stop/starts. It also got near 2000 PSI at one point. Pushed it around a bit but did not get to highway speeds. Going to take it out tonight to see how it performs.

For folks wondering why I switched the o-rings, I wanted an apples-to-apples comparison of the two HPFPs, and Viton rings are just not where the action is at (well, not on MY car anyway ) based on my not-good experience in January.

And a side note:

I remembered something else today -- the car started throwing thermostat codes shortly after I bought it, resulting in me replacing the thermostat + housing. I noted a good amount of oil sheen on the original thermostat surrounds at the time. HPFP #4 (the replacement for #3, which was damaged during shipping) started leaking oil from its internals -- not engine oil, but whatever is inside the HPFP for handling fuel pressurization -- about 2 months after install, and it was dripping that oil right onto the replacement thermostat housing, where it was just pooling away.

I know these things are known for needing thermostat replacement. But it occurs to me, given the amount of oil I saw from HPFP #4, and the fact that we've been circling oil loss (or other need for oil replacement), maybe part of the bottom line with this model of HPFP is that it leaks oil over time, period, and it leaks it right onto the thermostat -- eventually creating a good number of thermostat failures. Worth mentioning that my thermostat at purchase was original design, and when I replaced it I (obviously) replaced it with the redesigned one. Even with the redesign, the amount of oil that was pooling was more than I would ever want to be camping out for weeks/months/years on top of the thermostat housing.

I'll push the Mini with HPFP #1 around the highways tonight -- I'm pretty familiar with at least one road condition scenario that makes HPFP #2 stumble and throw the half-engine light, so I'm going to see if HPFP #1 exhibits similar behavior. Also off to find out once and for all what that oil inside the thing is.

 

I take this is a pending success story lol. Good job with the description. As you said about the TS, it could be another reason for limp mode.

 

Another update, for folks who wonder exactly how that solenoid is doing its thing. Someone made a video!

 

Yeah, the temp sensor was something I wasn't going to leave in a questionable state, for obvious reasons. Once I was clear that it was throwing codes on its own I replaced it. That was back in... well, awhile ago. But it was interesting to realize that the nature of the HPFP failure -- dumping oil -- might in fact be the cause of the temp sensor (by way of the temp sensor being where the oil lands and collects). D'oh.

So I took the Mini around last night as promised. Behavior of HPFP#1 is similar to HPFP#2 -- speaking broadly. I've gotten to the point where I can tell when these things are warmed up but can't keep up with the fuel demands -- there is a characteristic bit of stumble/hesitation. #1 and #2 don't stumble under exactly the same load conditions -- they seem to have their own trouble spots -- but when you feel the stumble, there's no mistaking what it is. And if the half-engine light is not on when it stumbles, it will pop on, and there will likely be a corresponding pending code thrown. One thing that is interesting -- and I don't recall this really happening with the Viton rings (original or otherwise) -- even if the half-engine light pops due to a PSI dip (or whatever), the PSI *may* quickly recover to and stay within within proper range, rather than the car going into limp mode (so long as you don't try to force the issue).

One thing that is interesting for sure is that part of the usability trouble is some sort of test routine done at startup. What I mean by that is that the car does something -- I don't know what -- at startup to decide whether the HPFP is capable. One way to defeat that -- in the case of both #1 and #2 outfitted with fluorosilicone o-rings (but not Viton -- this doesn't work with those) -- is to start the car and *immediately* get moving. Like the kind of get-moving you can do from roadside: start, drop into gear, hit gas, do not drop to idle. Whether a failing pump is is physically capable of providing normal-range PSI -- 620+ by my read -- seems to be a function of warmup, the oil question, and who knows what else. But if it *is* physically capable, if you do the start-and-get-moving, it will pop up to normal range (and if you keep moving, it will stay in normal range). Or at least that seems to be the case with both HPFP #2 and #1 after dropping in the fluorosilicone rings.

In terms of further diag, just about all of this points in my mind back to the units no longer having sufficient oil to handle the HPFP internals properly. I spoke with Blackstone Labs (www.blackstone-labs.com) and have ordered the test kit they indicated is best for the ID job. Will report back when I have results. Their website says 1-2 weeks to receive the kit -- hopefully it will arrive sooner.

Other than that, this leaves me with HPFP #3 (OSIAS, unused, shipping-damaged but possibly still usable), #4 (OSIAS, leaking oil and throwing half-engine light after 2 months in service), and #5 (new genuine Mini part, slated for arrival tomorrow).

 

New wrinkle: Blackstone website says they need 3 oz (a little over 1/3 of a cup) of oil to test. I don't know how much is inside the HPFP but... wellllll...

 

Hey TurbodTurtle -- you still out there? Wanted to get your present/updated thoughts on what kind of oil to use inside the HPFP -- meaning whatever is being compressed by the whole piston mechanism internally. I think I'm ready to tear that side of an HPFP apart and put it back together again, but I'm not sure I have enough oil from an existing HPFP to meet the 3oz minimum for a test/identify by Blackstone Labs.

Also wondering if by "transmission oil" you were referring to ATF -- or something else? ATF is generally pink here in the states, but the oil I've seen leaking from HPFPs is clear.

 

New genuine Mini HPFP arrived last night. Soooooo... this is what a properly-functioning HPFP cold start looks like



I learned something else last night while pushing the car around as well -- if you're in the wrong gear for the power demand you're putting on the car, it will throw a half-engine light aka CC-ID 029. Doing a bit of a throwback to an earlier set of posts, I have an automatic, and I tend to drive it in manual mode -- last night, with the new HPFP on, I was at highway speed in M6 and needed to accelerate. I needed to drop to M4 to get what I wanted, but I hadn't figured that out. Hit the gas, the car goes "bloop" and throws the half-engine light. Then the light bulb in my head came on and went "duh." So I recreated the condition, but dropped to M5. "Bloop," half-engine light. And then figured out why I was such a dunderhead about it -- lots of auto transmissions will still kick down if needed even if in "manual mode." This one doesn't. Duh. So this morning I just put it in "D" and leaned into similar acceleration scenarios -- no half-engine light. I even noted a couple of PSI dips under acceleration which, had I been in M6, would have certainly thrown the half-engine light -- but since the transmission kicked down in D, no half-engine light. So some of my half-engine lights in prior testing were absolutely self-imposed.

Anyway, all that said, I now have a functioning brand-new genuine Mini HPFP, and it appears to be performing to spec.

I also happened to be eyeballing the two OSIAS pumps I have -- #3 which I never used due to its shipping damage, and #4 which started leaking oil from the thermal compensator (or somewhere around it) 2 months after install. I had them both sitting upside down and the light caught the hole in the bottom of the thermal compensator. I can actually see a small amount of oil moving around in there. No oil to be seen in HPFP #5, the new genuine Mini HPFP. No oil to be seen in my two mostly-works-after-warmup genuine Mini HPFPs, those being #1 (2013-installed under car's first owner) and #2 (junker picked up on eBay in 2017).

The next thing for me to sort is what kind of oil is inside these things so that I can attempt to restore my other HPFPs. But all this leaky oil-loss stuff -- which has been pointed at in one other post way upthread citing a Mini service department diagnosing the HPFP as not having enough oil -- has me thinking there is some leak-prone internal component that can be identified.

 

Update: pushing the car around in "D" today, and threw a CCID-029/half engine light a bit over 80MPH. Historically that speed is pretty near where the car would tweak under HPFP #2.

Thing is, now HPFP #5 is installed -- the genuine Mini part, from a Mini dealership, and it has been in the car for a little over 2 days.

I'm not feeling any hesitation and such, the half-engine light clears after "reboot" (restart the car), and graphs are showing no oddities. So this leaves me with the following. Despite replacing:

- The LPFP
- The in-tank fuel filter
- The low pressure fuel line in the engine bay feeding the HPFP
- The HPFP
- The fuel pressure sensor

I still throw a CC-ID 029 -- that does *not* throw the car into limp mode -- under the most boring conditions. And no actual recorded OBD trouble code, of course, pending or otherwise.

I don't want to derail this thread -- going to keep this focused on HPFP rejuvenation -- but if anyone has any thoughts about what *else* has been observed to make the MCS throw a CC-ID 029 -- whether engine or drivetrain -- I would love to know.

 

Hello all,

I've just joined this forum as I really liked the level of investigation you are doing regarding this issue.
I have an 07 Cooper S, bought from a friend really tired of expending money to constantly repair this engine and now I'm challenging myself to understand this problem.
The HPFP fitted in my engine is the 3rd one after 230.000km and now is falling again. I'm very reluctant to just replace the whole thing and wait to fail again, and after reading this topic, I have some thoughts I would like to share with you.

I do believe the regulator O-rings may wear after years, and may be the cause of some of the HPFP failures, but I don't think they are the related to the most cases of failure. I'm still not convinced that some O-ring, used to seal a static part, could be so much influenced by temperature and brand new viton o-rings would not be enough to fix the problem if this was the cause.

The problem I have and as I'm reading seems to be the most common, is the difficult start, followed by engine stall or really rough idle. If you can start the vehicle and keep the engine in high RPM for some seconds, the car drives ok and the idle is almost fine.
Monitoring the rail pressure with torque APP, I can see the HP pressure is the same as the LP pressure in the start and in idle without pressing the accelerator. The pressure does not build up, as if there is a bypass from the LP to HP.
But if you crank and keep the engine in high RPM by pressing the accelerator, the HP fuel pressure raises up and then the car is normal.
Someone in this topic also noted this behaviour and wrote it looks like some diagnose of the fuel pump, that if the fuel pressure is not constructed in the first seconds, the HPFP would go into some limp home mode.
What I suspect is that the non-return valve is getting stuck when cold, and takes some time, temperature or fuel pressure pushing it to unlock itself and start to work.
I also think the pressure regulator could be stuck, or not working in this situation, leaving to the same problem. But in this case, after tearing the solenoid down and lubbing it, the HPFP would be better for some time, or at least for the first next start.

One more useful hint is the information from another topic, regarding the alleged root cause of the pump problems:
"The problem with the Mini Cooper S High Pressure fuel pump failing is an internal non return valve which fails and allows pressurized fuel to leak back into the fuel tank and as a result upon start-up has a lack of sufficient fuel to the injectors causing misfiring until the pump has built up sufficient pressure."

So, with this in mind, does anyone who has a bad HPFP in you desk did teardown the part and found the non return valve to check this part?

Another question. In my vehicle, when I switch off the engine leaving the key-on, the fuel pressure (HP side) stays around 100-120 PSI. What would be the correct value with a good pump?

LB

 

Bought a brand new OEM pump from Mini of Kennesaw in Georgia for about 250 shipped. It is made by BMW in the Czech Republic. Worked beautifully.

 

Prices must be coming down on these, or the market is getting flooded with crap parts.

Searching for P/N 13517592429...

https://parts.miniofkennesaw.com/pro...517592429.html
https://www.minipartsmass.com/parts/...&siteid=215989

Although, ECS still lists them for much more:
https://www.ecstuning.com/b-genuine-...e/13517592429/

 

I have seen the Czech pumps for sale from eastern Europe. I live near Kennesaw GA. and they are a Mini dealer. Mini is establishing a presence in the Czech republic - and the pump goes on a French engine in a car designed in Germany and built in England. The packaging was legit OEM BMW Group. It took about an hour to replace and the quote I got from another Mini dealer was 1700.oo installed. So I'm a smilin'. The only thing that I could be miffed about is that it 20.oo less than it was last week when I ordered it.

 

This is great news that the price of the pumps is back down to where it was a few years ago. Now i wish this happened a month sooner but oh well.

 

lfferraz (and others), sorry to be gone from this thread for so long. Things have not ended well here -- but not because of the HPFP. I suppose it's fitting that the HPFPs are now at $250-ish, as compared to the $530-ish I wound up paying for my replacement (also bought from a Mini dealer), and the $1500-ish we were seeing last year which was just insane.

I'll come back to talk tech later. The good news is that I have four (4) of these buggers in my possession. Yeah, don't ask, it just kinda happened, there is an explanation further upthread, lol.

Additionally, my CCID-029 that wouldn't go away looks like it was the turbo. No question that my turbo has issues -- we confirmed that, and I was going to replace the cartridge within. I figured once I had that done I would have a good test bed to experiment with the other HPFPs.

The bad news: some drunk doofus hit the side of my Mini a couple of months ago. Even though he only did body damage, the cost to repair and replace what he did damage to is way high (the work would involve a welding torch -- rear left quarter panel replacement). Because of the high mileage on my car, the repair cost/value resulted in the car being totaled, and right now I'm in insurance hell while they lowball the value from various perspectives.

So -- no Mini -- and no ability to test any HPFPs. Bummer. Yeah I'll get another, but in the meantime, I have a "fuel pump museum" on my kitchen counter...

I'll circle back and answer some of your tech questions, lfferraz.

 

lfferraz, I agree with a good amount of your analysis. When you remove the solenoid you've got three o-rings (one at the base between the solenoid and the pump body, two on the shaft. I personally found that flurosilicone rings I picked up from McMaster-Carr did a much better job with coming to temperature fast and all assorted implications therein. New Viton rings, by comparison, just stunk -- to the point where I would recommend switching to the flurosilicone rings for anyone who feels they have an HPFP issue and is willing to take it on. But I also agree that the improvement there is not the central cause of the HPFP issue. I think Continental made a poor choice of material in the pump design, plain and simple. I also noted in my work on the car that the sealing rings on the fuel injectors appear to be fluorosilicone rather than Viton -- I think the engine manufacturer was thinking the same way I am about contact with gasoline and ethanol-containing gasoline, and about temperature extremes.

There is a grey ring on the solenoid shaft that is sliced diagonally (Teflon/PTFE I believe, but can't prove) -- you can barely see the cut. I presume that this is operating as a check valve of sorts. I have looked at this on two, maybe three HPFPs (I've lost track) of varying ages and the ring has been in good condition on all. I do not believe it is the problem.

Separately, it did not seem to me that lubricating the solenoid in any way was needed or would be helpful. All moving parts in contact with fuel are inside the shaft, and in my case seemed to be moving quite freely.

Net, I think the solenoid in all cases is fine. Bad sealing rings can screw you up, but "fixing" them doesn't fix most of the baseline troubles.

That leaves the "other side" of the HPFP, which includes pistons that use some kind of internal oil to pressurize the fuel. I have not disassembled an HPFP to get into this part of the innards, but I had intended to up until someone collided my Mini . I remain curious about what kind of oil is inside "that side" of the HPFP and whether topping it off will do the trick for refurbishing the unit. From what I have been able to determine (some with the help of others in this thread) the core issue of the HPFP is that it leaks this oil out. I have one HPFP, an aftermarket (OSIAS -- stay away from at all costs), that began leaking this oil less than 1 month after installation.

The difficulty I have is determining what oil that is. Blackstone Labs needs 3oz of oil to analyze. Without enough oil to put in the bottle to ship away, I don't have enough to analyze, and if I take the risk of "emptying" all the HPFPs in my "museum" and get no concrete result back, all my HPFPs will be out of oil and unusable.

If you or someone else would like to go down the rabbit hole of sorting that piece of internal-oil mystery, I'm game. I mean, I have four HPFPs. I don't want to sacrifice them, I want to return them to operating condition, but I need help from people with more knowledge than I have to pull that off, especially when it comes to the oil ID question. If we can firmly ID the oil, and I can get the "other side" open, I'll fill one up and... well, I don't have my Mini anymore, but we'll figure out a test method one way or another.

With regard to your low pressure after you turn the engine off, 100-120 PSI is good. My Mini, after being allowed to sit around for a while after shutoff, would sit around 73 PSI (sometimes less, usually more). The pressure reading comes from a sensor in the fuel rail. The minimum pressure according to spec is 5 bar (72.51 PSI). With the car sitting idle for longer periods I have seen it go lower -- even sub-20 PSI if the car is allowed to sit for a VERY long time (don't ask ). There are certain without-starting things that are supposed to trigger the car to repressurize the fuel (such as opening a door) so that it will be ready when you hit the start button. I actually went through an extensive process of troubleshooting my LPFP pressure and replaced the LPFP and in-tank fuel filter out of an abundance of caution. My readings before and after the replacement were identical. If you're getting 100 PSI, your low pressure is not your problem. I also replaced my fuel pressure sensor. Readings tended to sit a little higher, I saw some 80 PSI more often than before where I had usually been seeing 73 PSI, but I think this measurement variance was inconsequential and it was clearly not at the root of my issues.

In the end, replacing the HPFP fixed the fuel pressure-driven issues. My other CCID-029 issues were tied to my turbocharger, though it took forever to dig that out. There is no question in my case that the HPFP itself was root cause of the pressure-driven issues. *Everything* else in my fuel system was fine.

That said, my advice to everyone now that the genuine Mini HPFPs are at the $250 price point is to just get a new one and self-install. That price is not only worth the hassle, it's worth the BMW warranty on the part, no question.

 

llferaz -- I edited the post above in some detail, so hopefully you read the edited version.

Since my Mini is collision-toast I decided to remove the solenoids on all four in the "museum" and discovered something new and interesting.

On the two OSIAS pumps -- distinct in that they were acquired in Q4-2017 -- the shaft of the solenoid is highly mobile. Apparently what's at the base is a ball joint, who knew, and it works just like you would expect a ball joint to.

In the genuine MINI HPFP that I think came out of a 2011-vintage junker, there is minor mobility. In the 2013-vintage HPFP that was in my Mini when I bought it (it was installed under a prior owner), there is no mobility to speak of, but enough give that I can tell it at one point should have worked like the junker one, and maybe the junker one was supposed to work like the two OSIAS ones. As best as I can tell, the OSIAS pumps are simply genuine MINI parts that OSIAS took some sort of cheap rebuild action on.

I don't really know the significance of this. One of the OSIAS pumps began to fail in my Mini, leaking oil all over the thermostat housing over the 2 months-ish it was being driven on and ultimately starting to throw the usual HPFP related OBDII trouble codes. The other has never been installed but was leaking oil when I got it (aside from a dent in an undesired place from being dropped on concrete by FedEx), hence no install.

I am inclined to think that improving the mobility on an old HPFP might help *something*, given that it looks like it may be designed to have some rather significant wobble/give in the first place. But I still think the "real issue" is on the piston/oil side of the Continental HPFP given all my observations to date, FWIW.

 

cjv2,
As everyone here, I just have bought a brand new pump... Here in europe the best price I found was around 350 euros, but brand new OEM.
I tried to tear down my HPFP, but the only thing I was able to remove was the solenoid. The O-rings were in good shape, but I have changed them anyway and sprayed WD-40 through all holes and let it act for a while, than I let drain all this oil. The solenoid looks very good, no signals of wear or deposits.

After this, I note the car running better, the surge issue in partial load is gone, but unfortunately the cold start is same as before. I still have low pressure readings in the cranking and idle, and I have to hold the engine in 3000rpm until the high pressure is achieved. Once the pressure is build for the first time, I have good readings all the time (700 at idle, 1500+ in acceleration). This indicates the solenoid is working fine and the pistons are being correctly lubed.
This is why my only suspect is that the non-return valve is stuck when the fuel pump is cold, and needs some pressure or temperature to be released.


I'm still waiting for the delivery of the pump to change it, and I'm afraid that besides of the HPFP, I might have some boost problem. The turbo is not kicking in in low RPMs and when it comes, it stays around 0,5bar of boost. The axle has no play, but is not spinning freely.
The car has 240.000km, and the turbo is still untouched. The engine is smoking and there is oil into the intake hoses. I already have bought a turbo rebuild kit and will inspect the diverter valve when the parts arrive.

I hope by this I can release most of the original power of this cooper.

Regards!

 

You are having exactly the same observations and pattern that I did. It's a dead match. That said, I have seen that across four HPFPs, with different extent of malfunction; and the question was how well they would sustain operation, under what conditions, and for how long. So I agree that the solenoid is working fine, but "the pistons are being correctly lubed" does not have clear evidence. It is worth mentioning that somewhere upthread -- I forget where -- someone actually got a BMW service diag report indicating that their HPFP had lost its oil. Given that the four in my possession either have lost a ton of their oil or are actively in the process of doing so (I keep the leaking ones upside down -- they all seem to leak out of the bell housing for some reason), I don't think this is a red herring.

In fact, going back to the OSIAS pumps -- as I mentioned I have two. This is because FedEx banged one on the concrete. The seller did not want to replace the pump regardless, and stated that the pump would be fine "as long as it wasn't leaking oil." They ultimately sent a second and didn't want the first back. The second one went in the car and was leaking oil all over the thermostat. The first, I've managed to deal with its dent, but it has not been put in an engine. As I look down into its bell housing, guess what? Accumulating oil. Turn it over and it drips. Yikes.

Also, the business of the oil with regard to the HPFP pistons is not to provide simple lubricant, from what I understand. The oil is used -- again if my understanding is correct -- in a hydraulic fashion. If that is correct, losing the oil is about the same as losing hydraulic fluid. The stuff that relies upon that hydraulic mechanism simply isn't going to do its job as designed.

I wish I could cite more precisely. I vacuumed up a *lot* of BMW and Mini HPFP technical reading, in addition to doing a lot of generalized reading on GDI pumps. That's where it led me, and that's why there's so much garble upthread about it. I would look into it further, if one wants to troubleshoot more deeply; so far you have landed at exactly the same spot I did in terms of observed behavior and circumstances after kicking the solenoid around a bit.

Re the turbo: FYI, if you are chasing around CCID-029 code with the half-engine light, low boost from the turbo will throw those just like low fuel pressure will. But the turbo issue never put my car in limp mode (governor tops you out at 4000 RPM) -- that seemed to exclusively be an HPFP thing. The turbo causing CCID_029s was the last thing I managed to chase down before someone hit my car and killed my troubleshooting, though I was planning the same rebuild operation that you are. You're 100% on a good track there, just remember that you won't be able to pull an HPFP-induced CCID-029 apart from a turbo-induced CCID-029. A dealer Mini scan tool can get you codes that give you more info, but that turbo stuff doesn't seem to tell much to the OBD-II side of the universe (unless it's pretty bad, I venture).

Hope this is useful?

 

lfferraz,

I'm trying to get my hands on a new hpfp for a reasonable price. Would you kindly share where in EU did you manage to find a pump for 350 EUR?

I tried ordering from Mini of Kennesaw in Georgia, US (zuc price is good) where exboyracer bought his new pump, but that dealers site is very misleading. When ordering they would even quote you a price for shipping to your country, but when proceeding to payment it would say that only orders of 100 000 USD would be shipped internationally. When asking for them to confirm if they do or don't ship internationally, I received an answer: "We do not ship internally."

Hopefully you might be able to help me with this. Hpfp's locally are in range of 8600 to 1000 EUR.

 

Wow, good thread, thanks!

 

Selis, these links may be of interest to you:

https://www.ebay.com/itm/MINI-OEM-07...YAAOSw0hlZNIQ7

https://www.ebay.com/itm/Mini-Cooper...UAAOSwjVVV2Ijo

There may be others out there. Both of these are for new genuine BMW/MINI pumps so far as I can tell. Avoid OSIAS aftermarket pumps at all costs (see my posts in the thread on those).

 

SO....after reading this WHOLE thread this am, is it worth it to update the o'rings on the solenoid of my OEM HPFP before I pull the trigger on a replacement? And would you say the non Viton material is a better choice out of the hole?

cjv2 I appreciate the time/effort you have put in even though you are without Mini currently.

Thanks!

 

 

Hey Rick, thanks for the inquiry. And as big as this thread got you've gotta have some endurance.

The conclusion I came to but never had time to dig in on due to my Mini getting bumper-carred was that the big issue in failed/failing HPFPs is loss of the oil inside the unit. That oil is used by HPFP-internal pistons in pressurizing the fuel.

I also concluded that if you have gotten as far/lucky to get that issue squared through some sort of teardown/rebuild, it is worth your time to replace the Viton rings on the solenoid with the specific fluorosilicone rings I got from McMaster-Carr. It's ridiculously cheap to do, the Viton rings definitely deterioriate (mine were brittle and one broke on removal), and leaving deteriorated rings in place is asking for trouble. The fluorosilicone rings are better for the purpose anyway (the big ring at the base and the rings on my injectors turned out to be fluorosilicone -- stock). That said, the *big* issue behind failure, based on detailed reports that are hard to find and easily overlooked (one is in this thread, in fact, from someone who only posted once or twice), looks to be the loss of oil.

This, by the way, dovetails with my experience with an HPFP rebuilt by a third party who said a shipping-damaged unit they sent was fine so long as it wasn't leaking oil. I got them to replace it anyway, and when the replacement was installed, it ran fine for a good spell only to eventually start having problems -- at removal, I found it had been leaking oil all over my thermostat housing. The oil, incidentally, drips out of the hole at the bottom of the bell housing on the unit (this was consistent across at least 2, maybe 3 HPFPs; the others either did not leak at all and were either working (brand new), or had run dry and were definitely not working (the oldest)). I never disassembled a unit aside from removal of the solenoid, so I was never able to find the source of the leak.

I agree fully with Geofox's comment immediately above: the HPFPs have gone cheap and the first best strategy is replacement. I don't know current pricing but looking around several weeks back I was spotting genuine Mini HPFPs below the $300 price point, maybe even $250. For a new unit backed by Mini warranty this is a no-brainer purchase, especially given the uncertainties of rebuild (clearly, nobody has figured out how to DIY that quite right yet). When I started this journey the Continental HPFPs were pricing at the $1500 mark so digging into DIY rebuild made the most sense. Things have changed.

As for me, my four spare HPFPs have become what a friend refers to as the "fuel pump museum" on an otherwise unused section of my kitchen counter. The engineer in me keeps saying "one of these days I'm going to crack one of these open and figure out what that oil is and where that leak is and I'm going to refill the bugger and see what happens." But I need another Mini to put it in first.

 

I know this thread is a bit old but it looks like NewTIS had the testing procedure and a description of what goes south on these pumps. Seems like temperature was a factor on those pumps CJ was shuffling around. They probably had differing amounts of oil left internally. I would imagine that this is some type of Vacuum pump oil. My wife has a freeze drying machine that uses a huge vacuum pump of similar design. The HPFP oil looks feels and smells just like it. I guess it depends how the pumps leak as I wonder if they truly cannot be refilled.


https://www.newtis.info/tisv2/a/en/r...nit/1VnXqS8AjN