What is the reason the HPFP fails so often

[Tallicia]

Is there any details on why the HPFP fail constantly? at roughly 100k miles and over the 65k miles in the last 3 years, I expect these to fail every 15k miles. pretty much the same as ignition coils.

1. It's ridiculous.
2. They are used on 100s of thousands of N55 and N54s
3. Why has the root issue still not been found, explained?

Yet after a decade, and BMW "extending" warranty to 120k miles, it's just a still a ticking time bomb.

Does anyone have any info on why these fails so gosh darned guaranteed much and what options there are to use something that has actual appropriate service life?

[dtla1]

Are you saying you've had to replace yours every roughly 15k miles? That doesn't sound right.

[JimD]

My personal theory is that any new technology is suspect for failure rate. HPFP is not really new at this point but when BMW started using it, it was pretty new. It seems like the engineers need some time to redesign the parts until they work well long term. Short term is covered by testing but it cannot reasonably be years long. I cannot prove this theory, but it is what I try to use. I stick with old technology when reasonably possible, for several years.

Cars are usually more dependable right before they are redesigned, in other words, not so much when they are introduced.

[Gangplank]

I thought it was only an issue on the N54?

[Soterios]

My guess is that either engineering or cost engineering overestimated the life of that part. They expected it to be able to handle a much longer duty cycle and it just flat out fell short.

[The Wind Breezes]

N55 does not have a HPFP issue as far as I know.

N54 was one of the first gen production direct injected gas engines. A lot of those engines had HPFP issues, not just BMW's.

[shawnyeeah]

My n55 hpfp was just replaced at 85K miles. But the part changed after 03/12 build date I believe, but mine was before that. Idk if the newer n55 will have issues

[duder13]

Originally Posted by yeezy4me

My n55 hpfp was just replaced at 85K miles. But the part changed after 03/12 build date I believe, but mine was before that. Idk if the newer n55 will have issues

Yeah, the pump changed on 3/12 and after cars, and I also don't know about failure rates with the newer pumps. My car car was built 5/11, so I expect mine to go at some point (only have 46K miles, though.)

N55 engines themselves are well built, but replacing auxiliary parts, like the waterpump, OFHG, and HPFP, is a just a part of living with the 135i, especially with a tune. I had two of the three go in the past year.


HPFP:

[Tallicia]

ugh, that's the vaccuum pump.

On the HPFP having disassembled all of them, mechanically, they seem fine.

Now there is the electric solenoid on the HPFP,, and BMW solenoids and electric motors/vanos/valvetronic, etc tend to have life of about the warranty, no more.

So I am looking to see if a proper high quality solenoid is the real root issue, related to duty cycles and it just being absolute bare minimum as per bmw standards.

Also there are a few gaskets, two which are just "external" basically keeping the motor oil inside the pump, which are not likley, and the 3 on the solenoid which controls the fuel into the high pressure fuel rail, or returns it to inlet.

Having a new solenoid and gasket kit for these would be ideal, to help determine if these are it, or if it's truly one of the 3 pumps, which even those are easily replaceable.

[Tallicia]

side note on the 3rd diagram the HPFP is marked 5, and it's a unit but consists of the front offset/slanted spinning pump/oscillating plate, the 3 pump cylinders, the electric solenoid, and the gaskets and handful of bolts holding it together.

it's a pretty simple piece all together.