Fuel tank shows half full only

My e36 was just filled up at the petrol station and the guage shows just over half full. What's wrong?

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If the guage moves to 0 when the ign is off most prob the tank sender unit is sticking. Do you have an OBC? if so does the DTE change at all?
The sender is not a bad job to do, then again its not the most fun either!
Regards,
Steve
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Level sensor sticking?
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The fuel level sending unit(s) are dirty. There are two of these units, one or both of them have dirty contacts.

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someone posted a method of checking all the light and gauges went to full scale etc recently, if that could be reposted, you could at least check that the gauge works...
T
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MW de Jager wrote:

Are you sure it was full? I've had a couple of situations with both my e46 and e36 that there were fumes or something in the tank that kept shutting off the gas hose. Since it shut off I thought it was full, but when I checked my gauge, the tank was only half or 3/4 full. Not a clue what caused it.
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Three hours later when I started it again, tank shows full. Must be an intermittend problem with a fuel sensor I think.

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It IS with your sender(s).
Mine behaved exactly the same way, I'd fill the tank and the guage would continue to register E. The needle would continue to fall, turning the Low Fuel Warning light, then after a few hours at work, the needle would jump to the F reading.
The dealership will tell you that you need new Fuel Level Sending units, but the contacts can be cleaned with relative ease and the sending units will work again. Mine has been working again for about a year now, and there is no sign that it will not be working again any time soon. In my case, the drivers side sending unit had gotten dirty, but there are two sending units, one on the left side and the other on the right side. Lift out the back seat cushion, pull back the vapor barrier, and remove the round cover. The sending units have a connector and a couple of hoses that have to be removed, then you can CAREFULLY use a punch and a hammer to tap the ring off. There is a special tool to remove the ring, but I used a 1/4" socket extension and a small hammer to tap the ring loose, and tight again. When you put the sending unit(s) back in, take care that you get the gasket in correctly, it can look like it is OK, but the tank will leak when you fill it to the very top.
Before you start this project, you need to plan your trips so you are at home with an empty fuel tank. The obvious admonitions of smoking and sparks should be observed.

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