tank venting hole

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Hi,
May anybody provide an answer to the following questions please ? How is the fuel tank vented on a Z3 (mod 2002) ? Where's the venting hole located?
TIA
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No fuel tank on any modern car, since at least the advent of OBD II has a fuel tank vent. (I believe it goes back even further.)
Perhaps you mean the return-air filter?
FloydR
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I'd like to make sure that, in certain circumstances, the hole by which the fuel tank internal pressure is balanced with the outside atm pressure, may not be cluttered. Following http://.bmwfans.info/original/z3/cou/ it's possibly the fuel tank breather valve external orifice. TIA
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That link is bad. Looking at www.realoem.com, try: http://www.realoem.com/bmw/showparts.do?model=CN33&mospidH093&btnr _0511&hg&fg You're probably looking for the dust filter (#6 on the diagram)
FloydR
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&hg&fg
The url points to the 2.5 inst of the 3.0i. Using the last 7 digits of the serial number I ended with the right model. I'm focussing on the fuel tank breather valve and the active carbon container which the upper tube is a fuel vent pipe. Hovever, I'm wandering where to locate them and how they're interconnected together and with the tank?
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wrote

That is not entirely accurate. There is a "vent" of sorts built into the gas cap that lets air into the tank, but prevents fumes from escaping the tank. The idea is that a cacuum can develop, so there is a flap kind of thing in the cap that will allow air to be sucked in, but this flap presses against the small hole to keep fumes from escaping in the event the tank builds pressure.
My guess is, he got a Check light with a code from the P044n family of codes that is telling him there is a Gross or Minor Leak. Odds favor such a code to arise out of the improper securing of the gas cap during a recent fill up.
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In the gas cap.
Therer is also a vent, of sorts, that comes through the charcoal canister.
I have to wonder what is making you ask such a question.

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Mainly because the tank's cap sucks in when I remove it. It's possibly the cause of the problems I currently have with the fuel gauge and the "---" displayed DTE.

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Does it suck or blow? The "---" is not vent related.
Let's do this, restate the trouble you are having, and we'll talk about the causes. I do not think the problems you have given are based in venting of the fuel tank, or lack thereof.

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Thanks Jeff for the help. The tank is under a slight depression. I also read horrors about tank deformations on 2000 Z3 resulting in gauge deteriorations and DTE issues.
Concerning the trouble: By accident, I refilled too much the tank although I was aware not to do that. First the DTE was correct, pointing to ~520 km as usual. Then 200 km later I noticed the "- - -" on the display, not blinking as it does when there's an emmergency to refill. Although the gauge was indicating 1/2, I stopped at the gas station and put around 25 liters. The DTE didn't change and the gauge continued to decrease like normal starting from the 1/2 until the light came on. Since, the needle remains at zero, I refilled something like 8 times without any modification on the displays.
The car has 98000 km on it, pampered and so. I already had issues at 50000 km but with the DTE only. It recovered by itself after 4 or 5 stops at the gas station. At that moment I already noticed that the thank was under a very slight depression.
The two problems look different. I can't manage to understand the link between the fuel gauge and the DTE. For me, it's the same value sent to both the gauge and the OBC to compute the DTE, based on the fuel consumption. As far as the gauge provides a readable indication, the DTE should follow and indicate a value accordingly. Otherwise the problem doesn't have the sender as a root cause.
Since I can't understand the DTE failure, I'm keeping investigating several ways: broken sender stuck against the wall of the tank, software error, bad data stored somewhere, waiting for reset, ... I've just ordered the TIS on e-bay to see how the circuits are wired. I also don't believe in a double failure. It should be more a propagation or a consequence.
By the way, you talked about error code in your previous message. Where are the error codes displayed on ? Do people read them using a tool or by depressing buttons in a specific sequence (odometer, contact key, OBC reset button, ... ) ? TIA

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Okay, now we have something to work with.
My E36 (a 325i) had this same problem. I would fill it with gas and it would continue to display Empty. Sometimes as I drove and parked, then started again, the tank would then read the current level, then drop as expected while driving. It would eventually get to E, and remain there after filling the tank.
The trouble was, one of the two fuel level sending units (your car might be different because it is a Z3) was dirty from sulpher or some other contamination in the gasoline. In any case, I pulled the back seat out of my car to access the gas tank through access ports inside the car, and removed the fuel level sending units and cleaned the contact pads.
There is a contact strip that is stationary, and a wiper that is attached to the lever arm. I used Contact Cleaner and a business card as the abrasive to clean the contact and the wiper. You have to be careful to not bend the wiper or your fuel level sending unit will be toast.
As you are working to pull the sending units, the obvious precautions will become apparent -- do not damage the o-ring, make sure you put the parts back in straight, etc.
On my car, the tank is under the back seat, on your car I would imagine it is in essentially the same place, except you haven't got a back seat. Perhaps your access to the tank will be through the trunk, I do not know. After I took the seat bottom out and pulled back some tarpaper-like material, there were two round access panels perhaps 4 inches in diameter and held on with 4 screws. Under these panels, there are plastic rings that have to be unscrewed, plumbing fixtures to disconnect and electrical connections to unplug -- this will release the sending units. There are o-rings here to be careful of. Assuming you have two sending units as I have, the Right Side unit is also the fuel pump. When I did my car, I did the left side first and got lucky because after I put the car back together, the problem was solved and I did not have to take the right side apart.
If you take this problem to the dealership, they will replace the sending units (one or both) at a cost of about $350 (for both) just for the parts. I had no trouble fixing my own sending units for the price of a can of contact cleaner.

Your car is an '02, so it is OBD II compliant. I'm not certain, but I think this should be pulled through the OBD II data port with a standard diagnostic scan tool. Autozone will pull the codes OR let you use the scan tool to pull them yourself free of charge.
I think you have discounted the sending unit (I also think there are two of them), whereas I think the sending unit is your trouble. There has been a problem with the fuel sold in the southeast that is reported to coat the fuel level sending unit's contacts with sulpher, which causes the sending unit to stop working. These reports date back a year or so.
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From the information I got on www.realoem.com, and similar sites, the car is equipped with only one sender, part of the fuel pump. It's located behind the passenger seat and the carpet needs to be cut. The following url provides some information with pictures. One of them represents the sender's tracks to be cleaned. http://www.z3club.fr/modules.php?name=Forums&file=viewtopic&t 72&highlight =jauge The message is in French, the forum needs free registration. Nevertheless it may be of some help for somebody else (here's my contribution :-) ).

Anyway, It's worth to give a try. Worst case: i'll have to buy another pump at a price pretty lower than the stealer's intervention. Best case it'll cost peanuts.
As soon as I receive the TIS, I'll start the surgery. Bye
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CUT? I think cutting the carpet is not required, you should be able to pull it back without cutting.
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The carpet comes already with a dotted line, look at the pics into the message I gave the url to access to. Quite sure that this is a huge work to remove the trims, I didn't check. Since I have time waiting for the TIS, I'll proceed to some investigatation more.
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Jeff Strickland wrote:

Not on a Z3. You have to cut the carpet to get at the hatch.
--
-Fred W

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Do you mean that the tank sucks in air as you remove the filler cap ? Because that would be OK.
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I should clarify an earlier statement ...
I said the gas cap allows air to enter the tank but prevents air from escaping. This is true. But, it takes a pretty strong vacuum to allow air to be sucked in, this can cause the cap to make a sucking sound when it is removed. This sucking sound is not only okay, it is desirable.
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^^^^^^ Do you mean that the smooth "ppsshhhtt" is normal ?
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Yes.
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