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fuel tank breather valve 2001 525

24K views 11 replies 4 participants last post by  bluebee 
#1 ·
What is this valve for and what problems would a person have if it failed
 
#2 ·
I can find no reference to such a valve. Are you sure of the nomenclature?

The tank is not vented to the atmosphere. All vapors are returned to the engine for burning.

Any leaks in the vapor recovery system will set a code. I don't believe it will adversly affect engine operation, but the car will fail a smog inspection.
 
#4 ·
#5 ·
That is also referred to as the purge valve which allows the intake manifold vacuum to suck the vapors out of the charcoal canistor.
 
#8 · (Edited)
Looks like the throttle body.
Thanks Jim. That's interesting because that means that large hose #3 to the throttle body (in red in the diagram above) is immersed in engine heat ... and therefore it probably deteriorates and might be the cause of vacuum problems:

So that others benefit from this knowledge, I'll add this information to the thread on identifying all the vacuum hoses:
- How to locate all the vacuum hoses in the E39 engine bay (1) & where to get those vacuum hoses (1) & what sizes to get for all the M54 engine vacuum hoses (1) & correcting the F-connector errors in the realoem diagrams (1).

Charcoal canister is above the left rear fender liner.
Thanks again.

It's interesting that the charcoal canister is so far from the engine; that means it has hoses that must span the length of the vehicle that could be troublesome.


I ran a search, but the best I could find is this E46 charcoal canister DIY:
- E46 (1999 - 2006) > LDP - Leak Detection Pump/Charcoal Cannister DIY

 

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#9 · (Edited)
For cross reference, we seem to have a need for a charcoal canister location & DIY thread based on what's in this thread today:
-> E39 (1997 - 2003) > Charcoal cannister 540- 2002

Searched but could not find the answer to the location of the charcoal cannisterl
I typed "/charcoal canister" in the bestlinks for you to find these:
- How to replace the LDP leak detection pump charcoal canister (1) (2) & does spilled gasoline go into the charcoal canister (1)

I think we should beef up our knowledge of the location of the charcoal canister & a DIY to test & replace it on both the V8 & I6 (if it's different).

For my part, I'll cross reference to this thread from there.
 
#10 ·
For the crosslinked record, this was posted today (with pics):
-> E39 (1997 - 2003) > E39 Leak Detection Pump DIY

Code P0456. Evap small leak detected. Smoke test found no leaks so I replaced original leak detection pump at 170,000 miles on 2003 530i.

Tools needed:

Flat head screw driver
8mm bit
10 mm bit
15 torx bit
Evap Leak detection Pump Part # 16137193479

Step 1:

Raise Car and remove rear wheel liner on driver side. Remove two 10 mm bit on both sides of shock absorber. Remove three 8 mm bits that are under wheel liner where mud flaps are. Remove four plastic rivets where wheel liner attaches to the body of the car. There are three on the side and one on the bottom.

Step 2:

Press and slide off leak detection wiring. Pinch the hose that is on top of the leak detection pump and carefully work it upwards until it is disconnected.

Step 3:

Remove three 15 torx bit screws that are under the leak detection pump.

Step 4:

Slide the leak detection pump outwards. Once the leak detection pump is out remove the rubber boot and install it on the new LDP.

Step 5:

Installation is reverse order.
See also:
- Fuel injection LDP leak detection pump DIY (1) & a fuel system charcoal canister DIY (1) & where is the fuel tank breather valve (1)
 
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