fuel pressure question

[jfoj]

@1iwilly

99% your vehicle has a soft failed fuel pump, I have seen MANY of these and have seen your exact same situation.

There could be a fuel level sender problem or a sucking jet pump problem, however, these are highly unlikely.

Forget about testing fuel pressure here for a few reasons. First due to the age of the vehicle/fuel pump and also due to the fact that static pressure at rest or idle is very misleading, you would also need to verify fuel volume as well.

But the simplest test which does not require you do get under the hood or get dirty is watch the fuel levels via the Hidden OBC Menu. Below 1/2 tank the passenger/right side of the tank should always have more fuel than the drivers/left side with the exception of a hard right turn sloshing fuel into the drivers/left side of the tank, but it should quickly be pumped back down by the sucking jet pump.

Replace the fuel pump and your problem will be resolved.

[1iwilly]

to me a softfail fuel pump means like my friends scion when is cold it starts on a dime after warm up if you shut it off it won't start you have to wait until fuel pump cools down the it starts with out fail
also i don't have a maybe start maybe not since the problem it starts on a dime a pump either works or not there is no in between which would be it work but the pressure would have to drop been the brushes are worn and not making good contact

Originally Posted by jfoj

@1iwilly

99% your vehicle has a soft failed fuel pump, I have seen MANY of these and have seen your exact same situation.

There could be a fuel level sender problem or a sucking jet pump problem, however, these are highly unlikely.

Forget about testing fuel pressure here for a few reasons. First due to the age of the vehicle/fuel pump and also due to the fact that static pressure at rest or idle is very misleading, you would also need to verify fuel volume as well.

But the simplest test which does not require you do get under the hood or get dirty is watch the fuel levels via the Hidden OBC Menu. Below 1/2 tank the passenger/right side of the tank should always have more fuel than the drivers/left side with the exception of a hard right turn sloshing fuel into the drivers/left side of the tank, but it should quickly be pumped back down by the sucking jet pump.

Replace the fuel pump and your problem will be resolved.

[jfoj]

Originally Posted by 1iwilly

to me a softfail fuel pump means like my friends scion when is cold it starts on a dime after warm up if you shut it off it won't start you have to wait until fuel pump cools down the it starts with out fail
also i don't have a maybe start maybe not since the problem it starts on a dime a pump either works or not there is no in between which would be it work but the pressure would have to drop been the brushes are worn and not making good contact

Not sure what you are stating, seems around her some call a cow a duck?

99% your fuel pump is on the way out, there can be many symptoms of soft failing fuel pumps. BMW pumps, Piersburg and Siemens/VDO seem to wear the brushes and often a few of the windings do not make good contact when running and the pump volume drops. This is one version of a soft fail pump.

As I stated, all you have to do is watch your fuel level in both tanks, the passenger/right side should never be lower then the drivers side. Most pumps have a 5000-6000 run lifespan. Keep in mind that the pump lifespan has NOTHING to do with mileage, it is all about run hours. For every second the engine is running, while you are stopped at a traffic light, stop sign, drive-thru or in stop and go traffic you are not accumulating miles, you are accumulating hours.

There are 2 extremes for vehicle users, Highway Warrior and City/Urban Dweller. A Highway Warrior may have over 150k miles for the same run hours a City/Urban Dweller may have with 75k miles. My 2006 E46 fuel pump failed at 84k miles, her car is a City/Urban Dweller. The Average MPH for most fuel fills is less than 20.

If I owned your vehicle, knowing what I know about Piersburg and Siemens/VDO fuel pumps, I would not think twice about purchasing a fuel pump.

[TiAgX5]

FWIW, I read the Bentley fuel system troubleshooting documents, no mention of any difference in the M54 system.

[TiAgX5]

WOW, really?

Over 200k miles, last +100k miles ALL work done on my X has been done by me (even alignments!), in my garage.

Same for the Vipers, ZR1 and E46 ZPP M54.

Only thing I have done by BMW is tire mounting and RF balancing.

[1iwilly]

problem fix with new fuel pump install thanks to all the reply
thread can be close

[jfoj]

Thanks for updating the thread, too bad the thread had to take the direction it did.

BMW uses different pumps across some of the chassis, some are Siemens/VDO, others are Pierburg. From the E46 chassis, the pumps are Siemens/VDO except for maybe the M3, and based on history, EVERY E46 should have a replacement fuel pump by now if you want a reliable vehicle.

Pretty much hold true for the E53 even if it may run a Pierburg pump, which it may as the E53 is a cousin of the E39.

For the pump price and the ease of replacement, it makes no sense to brag about how old or how many miles the fuel pump may have. I prefer to proactively replace electric fuel pumps by the cars 8-10th birthday because I do not like walking when I should be driving.

I think everyone will see that the E53 pumps will soon start failing in large numbers if they have not already started. The no starts tend to begin in the Winter months with the cold temps and after the vehicle has sat over night for a good cold soak. But before the pumps cause no starts, they get soft/weak and cause driveability problems and will cause the sucking jet/siphon pump to not work properly and the vehicle will also "run out of fuel" with the tank displaying 1/4 full.

I am sure everyone will have their own opinion and make up their own mind, but I highly recommend replacing the fuel pump as a preventative measure.

[X53Jay4.8is]

Originally Posted by jfoj

Thanks for updating the thread, too bad the thread had to take the direction it did.

BMW uses different pumps across some of the chassis, some are Siemens/VDO, others are Pierburg. From the E46 chassis, the pumps are Siemens/VDO except for maybe the M3, and based on history, EVERY E46 should have a replacement fuel pump by now if you want a reliable vehicle.

Pretty much hold true for the E53 even if it may run a Pierburg pump, which it may as the E53 is a cousin of the E39.

For the pump price and the ease of replacement, it makes no sense to brag about how old or how many miles the fuel pump may have. I prefer to proactively replace electric fuel pumps by the cars 8-10th birthday because I do not like walking when I should be driving.

I think everyone will see that the E53 pumps will soon start failing in large numbers if they have not already started. The no starts tend to begin in the Winter months with the cold temps and after the vehicle has sat over night for a good cold soak. But before the pumps cause no starts, they get soft/weak and cause driveability problems and will cause the sucking jet/siphon pump to not work properly and the vehicle will also "run out of fuel" with the tank displaying 1/4 full.

I am sure everyone will have their own opinion and make up their own mind, but I highly recommend replacing the fuel pump as a preventative measure.

This is sound advice.

[80stech]

Geeze I just changed the fuel filter and had to figured this all out on the weekend. I wish I had seen this post about the M54 not making use of manifold vacuum on the fuel pressure reg. I first assumed that someone had previuosly connected the hose wrong since mine had body work done on that side! I couldn't understand it because it looked factory but didn't make sense. I guess they didn't want to vent the regulator underneath the car and also make use of the same filter fittings/lines. Good to know for sure!

[oldskewel]

In defense of Bernoulli, and regarding the suction effect upallnight refers to ... assuming steady, inviscid, incompressible flow, sea level, port is perpendicular to the flow ... 100 mph air speed would result in a suction of 0.17 psi.

The 100 mph is a nice easy number which is way higher than actual. And 0.17 psi is not much. It's about how much atmospheric pressure drops when driving up a 300 foot hill.

My apologies for the standard units. This all seems to support jfoj's assessment.

Thanks jfoj for all the accurate information here. I recently replaced the fuel pump in my '01 with ~170k miles. Lucky for me it died while parked in front of my house. After cutting open the dead pump, everything looked great except that the brushes had worn past their limit.

EDIT - I wrote all the above after only reading part of page 1. The numbers don't lie and can cut through a lot of the problems with words and opinions. I forget who said it, but it was something like: "everyone is entitled to their own opinion, but they can't also have their own set of facts." Regarding the advice to replace pre-emptively based on mileage, I agree, but that is tougher when you know you don't have complete service records. Another thing in my case that was surprising was that there was no soft/flaky zone - it was running at 100%, then dead (failed to start one day - in fact it started up, ran for a few seconds and then died, luckily in front of my house, unluckily not in my driveway).