Engine Malfunction #2 Cause Found?

[ABMW]

Started my 35d today with 39 miles until empty showing on the onboard (gas station was closed last night) at 10:30 when I left work.

Started down a steep 10% hill, and all of the sudden "Engine Malfunction, Reduced Power" warning comes on.

This is the second time this has happened. However, the last time it happened I had a FULL TANK of Diesel fuel.

However, when it happened last, it was after parking it on a 10% hill, for about 30-mins., then coming out and starting it.

To me, this appears to be a fuel pump issue. I have 4,000 miles on my 35d and live in the Bay Area where 10% hills are commonplace.

There does not appear to be any type of failure with the fuel pump, as it should either work or not work, in my opinion. But, it appears that the manner by which the fuel pump is placed is not adequate to siphon fuel under certain circumstances.

Or, there's a true issue with the pump, but it's remarkably odd and I'm 100% it's confined to the fuel pump.

I understand it taking place with a near empty tank, but with a full tank?

Luckily, I limped to the gas station, at about 3 miles per hour (literally), filled it with 20-gallons and was on my way with no further issue. I was entirely confident the vehicle would start fine with fuel.

So what's the deal? There were 2.5 gallons of fuel left, but does anyone know I'm guessing there's a gallon tied up in the fuel delivery system at any given time, which would have left 1.5 gallons left.

Still, that's quite a bit and a 10% hill is just not that uncommon, in many parts of the world.

Any thoughts? Similar circumstances on hills, etc.? Has this taken place with anyone on a flat surface with a full tank of fuel?

[Craig]

I've had mine for over a year and never had this happen. I have never run my tank down that low. You said it happeneed with a full tank one other time... Does the dealer have any idea what causing this problem? Glad you were able to limp to a service station and not stranded...

Craig

[Lubehead]

This post makes me want to ask a question relating to running low on fuel. As a former owner of a GMC Duramax diesel, the owner's manual advised against running low on fuel as the fuel is used as a cooling medium for the pump as it is returned back to the tank. Does anyone know if the 35d engine fuel system design would be subject to the same caveat?

[Thunder22]

Originally Posted by Lubehead

This post makes me want to ask a question relating to running low on fuel. As a former owner of a GMC Duramax diesel, the owner's manual advised against running low on fuel as the fuel is used as a cooling medium for the pump as it is returned back to the tank. Does anyone know if the 35d engine fuel system design would be subject to the same caveat?

"as it is returned to the tank"?

I don't understand that, what do you mean?.

Diesel fuel and gas are petroleum products and they act as lubricants for the fuel pump and/or sending unit, not sure that they cool the pump except for keeping them lubricated, and without lubrication they will "burn out".

[ABMW]

Originally Posted by Lubehead

This post makes me want to ask a question relating to running low on damage. As a former owner of a GMC Duramax diesel, the owner's manual advised against running low on fuel as the fuel is used as a cooling medium for the pump as it is returned back to the tank. Does anyone know if the 35d engine fuel system design would be subject to the same caveat?

There's reference to damage to the vehicle due to running the vehicle low on fuel, but it does not specify what type of fuel. I was of the understanding that most vehicles had done away with this method of fuel pump cooling, but maybe BMW still cools their fuel pump via the fuel itself.

The point is, it happened once when fully fueled, and once when the fuel was low. The only similarity is the fact that both "malfunction" messages took place on a hill of around 10%.

The dealer's been less than helpful, as has BMWNA. The first time it happened, I was stranded for 3-hrs., with BMW Road Side and BMW Concord going back and forth, arguing via an SOS three way call as to how to handle the situation. I was in complete shock at the moronic behavior that took place.

The second time (today), I was 300-feet from the gas station.

The dealer, when pushed, did say that they've been having some issues with the high-pressure fuel pump. Apparently there are two fuel pumps on the 35d? Can anyone confirm?

But, it's an electronic device. It should work or not work. The first time it happened was on Day 3 of ownership with 300-miles on it. So, 3700 trouble free miles later, it's taken place again.

Both issues, were fuel starvation issues of some sort. The point is, what's causing them?

The hills, the fuel pump? Air in the fuel tank from the fuel swashing around when it's on a hill?

The strange thing is, that the first time, when I was on a full tank, the vehicle continued with its malfunction even when I came off the hill and was on flat road. It eventually went away after starting and cutting the ignition over a period of 3-hrs.

Odd...but sounds like BMWNA knows something and they're not saying, from the dealer's response.

[Penguin]

Originally Posted by ABMW

But, it's an electronic device. It should work or not work.

Electronic devices often experience intermittent failures. I once had an epoxy=potted voltage regulatory with intermittent failure that I could reproduce with a hair dryer, followed by an ice cube to temporarily restore function.

You probably just have a bad fuel pump which BMW will not replace until it experiences total failure.

[Lubehead]

I agee with Penguin. In reference to Thunder 22's query.... go to DPChip pump info. All about diesel injection pumps, how they work, history and developments. where you will find reference to the following statement:

"Because of the extremely high fuel injection pressure, the fuel in the return line becomes very hot, and a fuel cooling system is used to cool the excess fuel before it is returned to the tank"

So if the total fuel capacity available is low, the bulk fuel temperature will rise in the tank evidently creating an issue that compromises fuel pump/distribution component life as far as a 6.6L Duramax goes.

This is not related to ABMW's issue I am sure, it just prompted my question to those in the know if BMW's are susceptible to damage or compromised fuel component life by running low on fuel as the 6.6L Duramax engine is.

[MINIz guy]

We also got this message for the first time with our diesel. We were also driving up a few hills, one was probably 25% and the one we got the engine malfunction was on a 10% hill. We've also been dealing with DEF fluid freezing twice already, stalling issues and squeaky brakes. For a vehicle with only 2000 miles, this is unacceptable.

We have already talked to BMWNA about this. They also don't want to buy back our vehicle but have said something about replacing our diesel when the next big problem arises. We're still thinking about what to do next...

[ABMW]

Interesting, that they said they'd purchase it back after the next major repair.

I'm going to pursue a few legal options before I give up on the vehicle. As I mentioned in one other thread, that deals with this issue, I don't mind if I have to give up the X5.

But, I'm not going to lose a single penny in doing so, due to depreciation, etc.

Litigation would be a pain (but not to the point that I will avoid that route), but so too would losing $20 to $30k when I sell the SUV at a loss.

I have a feeling it won't go that far, but then again, I can't keep a $70k vehicle that only partially functions without a full resolution.

[Penguin]

Originally Posted by ABMW

I'm going to pursue a few legal options before I give up on the vehicle.

It might be best to move onto another brand.