HPFP

[Chuck76]

My HPFP went bad so it will be replaced and it only had 199 miles on the car. Just an fyi. It sounded like a humm or whine from the back driver's seat as others described.

[twin turbo]

I had mine replaced 2 weeks ago at 7K miles.

[teagueAMX]

Originally Posted by Chuck76

My HPFP went bad so it will be replaced and it only had 199 miles on the car. Just an fyi. It sounded like a humm or whine from the back driver's seat as others described.

BMW twin turbo direct injection engines have two fuel pumps - a low pressure pump in the fuel tank, that sits down low behind the seats and can make a humm sound. The second is the HPFP mounted on the engine. Either one can go out, but the HPFP goes out more often.

Dinan indicates that BMWs on board diagnostic software previously didn't issue a high presure vs low presure pump failure code. Due to all the known issues with the HPFP, dealership mechanics sometimes automatically replaced the HPFP but found out afterwards it was the tank pump. Clients had to go back for a "2nd pump replacement". Now BMWs has updated their on board diagnostic software to send a trouble code indicating which pump is bad.

If you don't hear the humm anymore, it's likely they replaced the one in the tank.

[SquireG]

Mine died aftr 2 months and 2 thousand miles. Car cranked for 3 to 5 seconds before starting and finally check engine light came on.

[JeF4y]

5500 miles and mine went. Took FOREVER to start and wouldn't idle. Then the next day it ran fine. Talking to others with this same engine/HPFP it's common.

Apparently the seals get eaten by ethanol in gas, so if you can avoid it you might consider doing so.

[teagueAMX]

Originally Posted by JeF4y

5500 miles and mine went. Took FOREVER to start and wouldn't idle. Then the next day it ran fine. Talking to others with this same engine/HPFP it's common.

Apparently the seals get eaten by ethanol in gas, so if you can avoid it you might consider doing so.

Damn - seems to me all the gas in California has it.

[SquireG]

Same in Florida. Can't avoid "gas may contain up to 10% ethanol". Seems like a poor design and one that will likely fail for us again......

[Chuck76]

Originally Posted by teagueAMX

BMW twin turbo direct injection engines have two fuel pumps - a low pressure pump in the fuel tank, that sits down low behind the seats and can make a humm sound. The second is the HPFP mounted on the engine. Either one can go out, but the HPFP goes out more often.

Dinan indicates that BMWs on board diagnostic software previously didn't issue a high presure or low presure pump failure code. Due to all the known issues with the HPFP, dealership mechanics sometimes automatically replaced the HPFP but found out afterwords it was the tank pump. Clients had to go back for a "2nd pump replacement". Now BMWs has updated their on board diagnostic software to send a trouble code indicating which pump is bad.

If you don't hear the humm anymore, it's likely they replaced the one in the tank.

How often does the rear pump fail versus the HPFP? This my first bmw, my previous car is a dodge viper gts and s2000 and they both had no problems of this nature.

Thanks for stating its the one in the tank. I didn't hear the noise when I first picked up the car from the dealer (it was a bit less than 1/2 full). I also heard (within threads of this forum) that a full gas tank will produce a more whine/hum, versus a lower fuel tank. If so, that would explain why I didn't notice the noise when I originally picked the car up. I still have quite a bit of fuel, 3/4th's full, and I'm going to attempt to run it down and see if the sound disappears. And if it does, is this normal?

I honestly can live with the hum/whine as long as its as intended. If not, they need to fix it. My appointment is on the 18th of this month. I had three techs check it out and they all state they can hear it. They even pulled in another Z4 next to mine to compare noises and the head tech said "yep, there's definitely a difference in the noise".

-Chuck

[teagueAMX]

Originally Posted by Chuck76

How often does the rear pump fail versus the HPFP? This my first bmw, my previous car is a dodge viper gts and s2000 and they both had no problems of this nature.

Thanks for stating its the one in the tank. I didn't hear the noise when I first picked up the car from the dealer (it was a bit less than 1/2 full). I also heard (within threads of this forum) that a full gas tank will produce a more whine/hum, versus a lower fuel tank. If so, that would explain why I didn't notice the noise when I originally picked the car up. I still have quite a bit of fuel, 3/4th's full, and I'm going to attempt to run it down and see if the sound disappears. And if it does, is this normal?

I honestly can live with the hum/whine as long as its as intended. If not, they need to fix it. My appointment is on the 18th of this month. I had three techs check it out and they all state they can hear it. They even pulled in another Z4 next to mine to compare noises and the head tech said "yep, there's definitely a difference in the noise".

-Chuck

Yes, if your dealer replaced a fuel pump that dealt with a loud behind the seat hummm sound, it was the low pressure pump in the tank. It's not uncommon for fuel pumps to make that sound, especially when you first start the car, but it should subside rather quickly after pressure builds up within your fuel lines.

I don't have information on how often they go out, but after reading a few very long threads on the e90post forum it's clearly a problem. The e89 Z4 (2009-2010) 35i have the same twin turbo n54 engine the BMW 335i uses which have been plagued by this problem for some time. BMW extended their HPFP fuel pump warranties to 120,000 miles. Even though BMW indicates they have a new HPFP design it doesn't seem to have helped considering that newer cars are still having the problem.

A number of cars are using direct injection fuel systems these days so one has to wonder why BMW can't seem to get this problem corrected. BMW's new(er) 4.4 L v-8 design 1st used in the x6 50i has direct injection fuel systems and I haven't heard of this problem with their engines. Porsche's newer twin turbo have direct injection and to my knowelage no issue. Somebody else may heard something on it. As you stated the Viper and the Honda S2k haven't exhibited a premature failure scenario, either. BMW - what gives?

Conventional advice for in-tank fuel pumps is try not letting your fuel levels drop below 1/4 tank as the pump needs to be submerged in fuel to stay cool and to last a long time (typ 80-100,000 miles). But if the problem as JeF4y pointed out, the ethanol blend is attacking the pump seals, there really isn't much you can do. If that's the case, it should be a no brainer to fix because ethanol based fuels ain't exactly new tek.

The sound from the pump and the 1/2 vs full tank scenario seems counter intuitive to me. I would have expected the higher fuel levels to dampen the sound rather than enhance it, and the 1/4-1/2 full tanks to be louder due to a sound resonance in the tank, but oh well, you learn something new everyday.

Cheers, FWIW and I hope it helps.

[Chuck76]

HPFP online petition.

http://www.petitiononline.com/fixpump/petition.html

[SquireG]

Failed fuel pump in first two months = me signing petition.

[dcs2k]

damn seems like mine looks like its failing too

What codes are you guys seeing before it went bad?

[Chuck76]

Well when I got mine replaced, it wasn't the front but the rear. So it was not the HPFP. It definitely sounded like a whining coming from the rear.

[rmorin49]

HPFP failure is happening in every BMW line that uses the TT 3L engine. I don't have the numbers in terms of percentage but if you go to the bimmerfest 3 series board you will see lots of posts about HPFP failure. Unfortunately this will likely be the case with the Z4 as well. BMW has changed suppliers of HPFPs at least once and maybe twice. However, it seems even the latest FPs are subject to failure. Whether or not the cause is ethanol is still being debated.

[Otago]

is it true the problem fuel pump issue for 35i only?

[mikeinaustin]

the "ethanol" issue for the hpfp has been disproven. even if 100%, you could not destroy the seals in < 200 miles. bmw has been using these pumps for years, redesigned about 5 times and changed suppliers as well. if it were as simple as ethanol content, it would have been fixed many years ago as that is something extremely easy to design for, test, verify and produce.

[teagueAMX]

Originally Posted by Otago

is it true the problem fuel pump issue for 35i only?

Only the Z4 35i, but other BMW models with the 3 liter twin turbo n54 engine have this problem as well.

Originally Posted by mikeinaustin

the "ethanol" issue for the hpfp has been disproven. even if 100%, you could not destroy the seals in < 200 miles. bmw has been using these pumps for years, redesigned about 5 times and changed suppliers as well. if it were as simple as ethanol content, it would have been fixed many years ago as that is something extremely easy to design for, test, verify and produce.

+1


Does anyone have an idea why the pumps are failing or what part of the pump is going bad?

It's interesting there's a lot of discussion about the HPFP, but it sounds like based on reading posts here and elsewhere about a third of the pump replacements are are actually the rear in-tank pump. I talked to a mechanic who routinely repairs BMWs and he confirmed this, and said that the HPFP is often mistakenly replace the HPFP when in fact it's the rear pump.

[Kief]

My HPFP was replaced on my '08 E92 335i at around 7k. Only indication of trouble was a few long cranks at start up. No problems afterwards and the warranty for the part was extended as previously mentioned.

[rmorin49]

Originally Posted by teagueAMX

Only the Z4 35i, but other BMW models with the 3 liter twin turbo n54 engine have this problem as well.

+1


Does anyone have an idea why the pumps are failing or what part of the pump is going bad?

It's interesting there's a lot of discussion about the HPFP, but it sounds like based on reading posts here and elsewhere about a third of the pump replacements are are actually the rear in-tank pump. I talked to a mechanic who routinely repairs BMWs and he confirmed this, and said that the HPFP is often mistakenly replace the HPFP when in fact it's the rear pump.

I think your mechanic is confused. The HPFPs that are failing are not in the tank, they are in the engine compartment. The primary pump in the tank simply sends the fuel to the HPFP, then it is forced under very high pressure into the injectors. It is the HPFP that are failing, read all about it in the bimmerfest 3 series, E9X forum.

[teagueAMX]

Your right, the pump in the tank is not a HPFP (note my lengthy post above), and I have read the rather extensive posts on this subject.

What he was saying is that the HPFP failure was occurring so frequently that mechanics automatically assumed the problem was a HPFP failure, and sometimes mistakenly replace it. They inadvertently ended up replacing both pumps, requiring longer shop time or in a few cases requiring the owner bringing the car back for another repair. It was happening often enough that BMW had to develop a code in the ECU to positively identify which pump was actually failing. The point is that the already infamous HPFPs reputation was made worse and owners further inconvenienced by poor diagnostic work.

[mikeinaustin]

keep in mind though, like any car, the fuel pump (normal one in the gas tank) can fail like any other part of the car. for the normal pump to fail though, it would basically just be bad luck. i believe it has actually already happened to one member of this forum, but again, just bad luck.

[nin1616]

I had the fuel pump replaced on my 335 twice.

That's one of the reasons why I went with the 30i Z4 instead of the 35i.