Gas Guage Stuck

Hi all --
We have a 1998 Z3, 2.8 litre. The fuel warning light came on yesterday, so my wife drove into a station and filled up the tank. When she
started the car up again, the needle on the fuel guage went to its previous position (almost empty) and stayed there. The odometer reset fine, and the rest of the electronics seem to be functioning, but that needle won't move off empty, and of course the warning light is still on.
Any ideas?
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The fuel level sender is probably bad or dirty. The bad news on a Z3 is that you need to remove the passenger seat and do some minor surgery on the carpet to access the fuel pump. The good news is that once you've gotten it out, its pretty easy to either replace the sender or clean off the contact strip that gives the fuel level. I can email you the pages from the TIS on how to do this if you'd like.
Kyle. 98 740iL 97 M3
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@tampabay1.rr1.com says...

Thanks. Sounds like a plan. I spoke to the servicer today, and he said this is a saddle tank with two sensors. Either one could be corroded, and worse case is that they have shorted each other out and both need replacing.
Will e-mail you my real address.

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I suspect the sensors have NOT shorted each other out.
Mine would show E after filling the tank, but would jump to the correct level later on. The sensor on the right side is part of the fuel pump, the sensor on the left side is only a fuel float. In my case, the sensor on the left side was the culprit.
Once the float assembly is out of the car, you can easily find the contacts. You can clean the contacts with contact cleaner and a business card. Use a rough-surface business card as a sort of sand paper to clean the black build up from the contacts. You can use a type writer eraser (the pencil-type with the brush on the opposite end that is rougher than a simple eraser).

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@tampabay1.rr1.com says...

And . . . It started working again. A local club member recommended using a high detergent gasoline for three or four tanks, and seeing if that cleaned the contacts. We're going to try that and see if it clears up for good.
Perry
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says...

It won't clear up for good.
The symptom will come and go, and eventually will come and stay. The sending units on the sedans and coupes are easy to get out, I think the Z3 may prove to be more difficult. The difficulty comes from where the tank is in relation to what is directly above it. If the seats are over the tank - and I have no clue if they are or not - then they will need to be moved first.
The tank is easy to access. Pull the carpet out of the way and there is a round cover (one on each side of the car). Remove the cover, 4 screws, then remove the fittings and finally take the ring off that holds the sending unit in place. Lift the sending uint out and take it to your bench for a cleaning service. Reassemble in the reverse order.
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Jeff Strickland wrote:

Here's the scoop on Z3's:
<http://www.mz3.net/articles/244.html
-Fred W
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sending
prove
and
first.
a
then
So Fred, there's only one sending unit in a Z3? Hasn't that car got a saddle tank with two lobes like the coupes and sedans have?
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Jeff Strickland wrote:

Yes, you are correct. One sensor. Tank has one main compartment, no saddle.
-Fred W
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The servicer told us two tanks on the '98 2.8 litre, two guages. The one on the left is $470 USD to replace because it is with the pump, and the one on the right is $230 USD. We are letting it ride for a while.
Thanks everyone. Having this group here makes the whole BMW process a LOT easier!
Perry
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Shadowdancer wrote:

On a '98 2.8 liter Z3? Nope. He's dead wrong.
No need for two sensors as the tank is not saddle shaped as on other 2 series cars.
I verified that there is only one sensor from the ETK parts catalog and also in the 1998 Z3 ETM manual. It shows only the one sensor "installed in fuel tank", where-as on a 328i of the same year it shows a saddle tank and two sensors.
I'm thinking that your servicer does not know Z3's all that well...
-Fred W
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Malt_Hound@*spam*yahoo.com says...

I'm thinking I agree with you. And he's at the dealership in Louisville.
Perry
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Shadowdancer wrote:

Heh... why am I not surprised?
You know, thinking back on this, I bet the fact that the Z3 has only one sensor compared to the 3 series (not sure about the 5's and 7's) is a big reason that we hear these complaints about flaky gas gauge more often on them. I could be wrong, but I recall that on the cars with two sensors the gauge reports the *higher* of the two (not the average as you might expect) so if one sensor flakes out for a while you might not even notice it.
-Fred W
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saddle
Perry, I suggest you give a whirl at servicing the sending units yourself. It is really quite easy if you are inclined to tinker with stuff. If tinkering isn't your cup of tea, then reset the odometer with every fill up, and always fill up, then you can reasonably go 300 miles until the next trip to the pump.
PS My dealer quoted me prices about half of what you got, but that was just for the parts. If your quote includes the labor, then it sounds a bit high, but not hugely high.
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There are two Fuel Level Sensors, one of them is dirty.

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