which fuel pump to change
 

long story short wife gut stuck last night on way home from work gas gauge showing a tad over 1/4 of a tank but was starving for gas as to when key on push in shrader valve i would hear air but no fuel at all put 5 gallons in started right up. my question which fuel pump meaning pushes fuel from one tank to the other.when low.??? thanks
02 x5 3.0

Transfer pump.

But try unplugging it from the driver's side fuel level sending unit and replacing the o-ring first.

Thanks will try that is the oring available at regular auto parts stores.also what about the transfer tube.??

Your siphon pump (aka transfer pump) fails.

The work-around solution is to keep fuel ALWAYS above 1/4.

Ditto g3ood...the syphon jet is on the left side (driver's side LHD):

Ok thanks for the replies where would be a good source to get a new pump besides the stealer

Siphon Pump is PN 16111184427:

RealOEM.com - Online BMW Parts Catalog


About $86 at dealer...

BMW Parts - Chevrolet GMC Cadillac BMW Mercedes Benz Parts and Accessories

thanks for all the replies will look into this tomorrow $86.00 not bad price

I'm not sure on the size of the o-ring but it shouldnt be hard to find.

Pump has no moving parts, it stops pumping if it develops a leak that breaks vacuum, usually at the o-ring where it plugs into the left tank fuel level sender.

I developed the same problem and it turned out that the locking clip of the siphon pump was damaged when I replaced the fuel level sending unit previously. The siphon pump connection would work its way loose and stop pumping.

Fixing the locking tab solved the problem and I didnt have to change the pump.

Others have found the connections fine but have seen the o-rings hardened and brittle.

Worth a try to check first IMHO. Potentially a few cents vs $86. :)

thanks where can i get a better picture to look at i was able to take pump out 1/2 way but could see how to disconnect the hoses thanks

The o-ring is actually listed, #4 in the realoem diagram linked by cn90 above.

Apparently it's a 22mm x 2mm FPM o-ring.

You dont have to pull the whole sender out, lift it a bit and you will see the siphon pump plugged to the sender body, reference the realoem diagram.

Unplug the siphon pump from the sender body and you'll see the o-ring.

ok thanks got it apart oring still looks like new not hard or brittle but it was kind of pinch when taking syphon bracket off put it back together will see when i get down to a 1/4 tank again

Hopefully it works. Also, do check that the locking tab and the ledge it engages are intact. They will work loose if it isnt.

When you get close to 1/4 tank, use test 6 on the OBC. If the siphon pump still isnt working, you'll see the right tank going to zero while the analog gauge is still showing 1/4 tank.

ok how do you read this meaning=look at pic i'm showing a tad over 1/2 tank but the middle option 6 say 9.4 on a 24.3 gallon tank if full is 24 gallons then 1/2 should be around 12???

When you go to the behind the scene data like the OBC Tests...distance is measured in kilometers, temperature is measured in Celsius, and liquid capacity is measured in liters.

So the interpretation of OBC TEST 6 is that you have a fuel tank with the capacity to hold 93 liters of fuel...1/2 tank should be approx 46 liters. But since the e53's gas tank is slightly different than the e38/e39/e46 where their tanks are divided equally in half...the e53 has a larger capacity on the left side of the tank vs the right.

The interpretation of OBC TEST 6 in the pic you posted is...the left fuel sensor is registering 39.6 liters of fuel, the right fuel sender is registering 9.4 liters of fuel. and the integer on the far right is an approximation of total fuel remaining in the tank which is registering 49 liters. This is pretty consistent with what your fuel gauge is registering...a little over 1/2 tank of fuel (with 93 liters being the capacity of a full tank).

See the information below for another or better explanation on how to interpret OBC TEST 6:

thanks the math says 49 Liters (L) =12.94443 gallons
so its accurate

:thumbup: