TWO fuel pumps.. Really?

[Kristophe]

Xoutpost has been incredibly helpful with my 2001 X5 3.0 when tackling annoying issues such as the infamous Final Stage Relay dead battery in the morning syndrome and the driver's door Carriers Gone Kaput. But granted when the fuel pump went out at 140,000 I couldn't really hold that against her. I took it to an indy BMW shop my cousin takes his wife's X3 to but it died in the road a week later when my daughter was driving and had it towed back. Here's the kicker; he said there's actually another pump in the tank that pumps low fuel volume to the main fuel pump and it now must be out and wanted $300 to replace in addition to the $500 plus I already paid for the main fuel pump replacement. I passed on the offer and I'm not finding any such "auxillary" fuel pump as a replacement part so is he pulling my leg? The truck does run great until it gets past the yellow light.

Thanks much in advance

[X5SND]

I'd find a shop that knows what they're talking about --- There is only 1 fuel pump, and it's in the tank.

[Kristophe]

Yes there's gotta only be one stinkin' fuel pump. This is the first BMW I've owned. I had high hopes for this shop but you're right I think I need to look elsewhere. It must be the fuel filter.

[Lowblock]

Isnt there a "transfer" pump like there is in the E39?

[X5SND]

They probably changed the filter/pressure regulator. It kind of looks like a fuel pump (just the pump, without the level assembly) --- Minus the electrical connections....

[nate13]

There is a suction pump that goes between the saddle of the tank, and is driven by your main fuel pump. Replacing your fuel filter will help as there is less back pressure, but the thing to do is fish around in there and make sure it's connected and clean (and free of holes/ damage!). I have an ongoing issue with my 330 dying on the highway on less than a quarter tank, but only if driven extended periods. I've since changed my habits and fuel up at 1/4 or more. Too much money for such an odd problem!!

[Kristophe]

Thanks Nate. So its more of a gravity feed device rather than an actual secondary fuel pump? For some reason I haven't come across any digagrams that shows such. It is common on BMW?

[TwinsPoppa]

Is it #6? Or is that just the cable w/o the pump?

Another thing, why does the description on the fuel pump say "delivery unit, right". Are there two pumps? I don't see a "delivery unit, left"

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RealOEM.com * BMW E53 X5 3.0i Fuel pump and fuel level sensor

[JCL]

There is one pump in the tank, in the classical sense of an electrically driven fuel pump. BMW calls it a fuel delivery unit. On the X5, it is on the right side, it is the fuel pickup, has a pump built into it, and contains a fuel sender. Since it is a single unit, they use the term fuel delivery unit.

There is a somewhat similar unit on the left side, but without the pump. It is usually replaced when the sender dies, but all it is is a sender and fuel pickup for the left side of the saddle tank.

There is another unit in the tank called a fuel sucking pump, but that is a poor translation from German, IMO. It has no moving parts, and no motor. It is not driven. It is a siphon valve, so that returning fuel (from the fuel return line) goes through a venturi and creates a suction that draws fuel from the left side of the tank to the right, where the electric pump sits. It can't wear out, since it is a static piece of plastic. It is highly unlikely that it needs replacing.

What does happen is that if the fuel filter is partially clogged, then there is less return fuel flow, and the suction pump (venturi) doesn't create enough suction. That isn't a suction pump problem, it is a clogged fuel filter issue.

[TwinsPoppa]

Originally Posted by JCL

There is one pump in the tank, in the classical sense of an electrically driven fuel pump. BMW calls it a fuel delivery unit. On the X5, it is on the right side, it is the fuel pickup, has a pump built into it, and contains a fuel sender. Since it is a single unit, they use the term fuel delivery unit.

There is a somewhat similar unit on the left side, but without the pump. It is usually replaced when the sender dies, but all it is is a sender and fuel pickup for the left side of the saddle tank.

There is another unit in the tank called a fuel sucking pump, but that is a poor translation from German, IMO. It has no moving parts, and no motor. It is not driven. It is a siphon valve, so that returning fuel (from the fuel return line) goes through a venturi and creates a suction that draws fuel from the left side of the tank to the right, where the electric pump sits. It can't wear out, since it is a static piece of plastic. It is highly unlikely that it needs replacing.

What does happen is that if the fuel filter is partially clogged, then there is less return fuel flow, and the suction pump (venturi) doesn't create enough suction. That isn't a suction pump problem, it is a clogged fuel filter issue.

Thanks for the explanation. Looks like the OP needs a new shop and check the fuel filter as previously mentioned.