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bimmaster
bimmaster, BMW Technician
Category: BMW
Satisfied Customers: 1881
Experience:  3 years dealer experience, master bmw tech
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I got a problem with my 1998 bmw 750il fuel tank. It is vacuum

Resolved Question:

I got a problem with my 1998 bmw 750il fuel tank. It is vacuum in the fuel tank cause the tank noise and collapse and leak. Now I gonna replace for 4th tank. My mechanic could not this problem. It is very hard to find out good condition used 750 il fuel tank.Would you please recommend me how to fix this problem, I do not want to replace fuel tank again and again.


Thank you very much for your assistance.

Tom Kosol
Submitted: 5 years ago.
Category: BMW
Expert:  bimmaster replied 5 years ago.
Hi two points to Check would be a bad gas cap not allowing air to enter the tank. The cap should hold pressure, but not vacuum. As the fuel is pumped out, it needs to be replaced with air. Try a new cap with the tank. And periodically check the tank for vacuum by opening the cap and listening for the vacuum release.

Second being a stuck open purge valve in the engine bay. This valve should cycle to Evacuate fuel vapor from the charcoal canister. If it's stuck open it's possible there would be too much vacuum in the tank.
Customer: replied 5 years ago.
Thank you for your answers, As your answer for the first point, I have changed gas cap several time but it could not solve the problem. But the second point , I will ask my mechanic to do that as your recommendation.
By the way, I have ever bought a new model purge line canister part # XXXXX 13 1 184 554 to replace the old one follow by www.E38.org recommendation, but it was not fit to my car. I did not know what wrong.
Would you please give me more information about part # XXXXX how to replace it.
Thank you very much for your further recommendation.

Tom Kosol
Expert:  bimmaster replied 5 years ago.
The part # XXXXX gave was for a vent line on a 740il, or a 528i/540i. So that likely wont fit your 750il.

I have uncovered the bulletin for this very same problem that involves replacing the purge line with an improved part. See copy of bulletin below. I will attach pictures separately.

SUBJECT: New Evaporative (Charcoal) Canister Purge Line
MODEL: E38 and E39
Situation: A new style evaporative canister purge line has been introduced into production on all E38 and
E39 models approximately 3/97.
The function of the purge line is to allow outside air to enter the fuel tank via the evaporative
canister. This equalizes pressure in the fuel tank as the fuel is drawn out during engine
operation.
The one end of this line is open to atmosphere and the other end is connected to the center
fitting of the evaporative canister.
If the evaporative canister purge line becomes restricted or clogged the resulting vacuum in the
fuel tank will cause the tank to partially collapse.
The customer complaints may be:
A knocking or a tin canning type of noise from the fuel tank area of the vehicle and / or when
removing the fuel tank filler cap a hissing noise is heard (pressure equalizing in the tank).
Cause: Investigation of restricted or clogged evaporative canister lines has indicated the following three
possible causes:
-- line pinched
-- rubber grommet not seated correctly between the center fitting of the evaporative canister
and purge line
-- insect (spider) nests
Note: If this type of line restriction is found blowing through the line with compressed air will
not remove the nests completely due to the sticky nature of this substance. The line must be
replaced in this case.
Correction: If the above customer complaint is received and the evaporative canister purge line is restricted
or clogged on vehicles produced prior to 3/97, it should be replaced with the new style purge
line.
The new style purge line (1) is now shorter than the early style line (2) and incorporates a plastic
screen on the end which is open to atmosphere as shown in the illustration below. The screen
prevents unwanted objects from entering the open end of the line which may cause restrictions
or a complete line blockage.
SI New Evaporative (charcoal) Canister Purge Line BMW AG - TIS 11.09.2003 20:00
Issue status (10/2001) Valid only until next CD is issued Copyright Page - 1 -
Procedure: Evaporative canister purge line removal and installation:
Remove the left rear wheel.
Remove the left rear wheel housing trim.
Note: On vehicles equipped with self
leveling suspension the line which passes
through the wheel housing trim should be
removed at the accumulator.
Refer to the repair manual section
32 13 006 for power steering bleeding
instructions.
Remove the expansion tank and
evaporative canister. Lines remain
attached.
Remove the purge line from the center
fitting of the evaporative canister.
SI New Evaporative (charcoal) Canister Purge Line BMW AG - TIS 11.09.2003 20:00
Issue status (10/2001) Valid only until next CD is issued Copyright Page - 2 -
Remove the purge line from the top of the
expansion tank.
Remove the purge line from the inner
wheel house clip and pull the other end of
the purge line out of the body duct.
Note: On E38 models an additional plastic
hold down clip is installed on top of the
fuel tank (not shown) to secure the early
style purge line. A forceful pull will be
required to remove the line from this clip.
Install the new purge line on top of the
expansion tank and connect the open end
to the center fitting on the evaporative
canister.
Note: Make sure that the rubber grommet
is seated correctly between the purge line
and the evaporative canister fitting so it
will not restrict or block the air flow.
Reinstall the evaporative canister and expansion tank.
Reinstall the left rear wheel housing.
Reinstall the left rear wheel.
Parts Information: Part Number Qty. Description
16 13 1 183 996 1 Purge Line E38
16 13 1 183 997 1 Purge Line E39
graphic
Customer: replied 5 years ago.
Thank you very much for your further information. I have ever read this papers before from www.E38.ORG. I have ever bought part that you mentioned ( 16 13 1 183 996 1) from BMW dealer near my place. But you know what this item change part number to be # XXXXX 13 1 184 554 that I refered, I rechecked from his computer, it's correct.So now I have still kept this part in my garage.
If you have more information about this problem for 1998 BMW 750 il, please email me asap. I will ask my mechanic try to do a stuck open purge valve in the engine bay.that your recommendation. Sorry to bother you again, thank you very much for assistance.

Tom Kosol
Expert:  bimmaster replied 5 years ago.
That is all I have on this problem, the improved line needs to be installed per the instructions, and it should fix this issue for you.
bimmaster, BMW Technician
Category: BMW
Satisfied Customers: 1881
Experience: 3 years dealer experience, master bmw tech
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