Problem with the fuel indicator - United Bimmer Community

**d3uterius** · 05-09-2008, 06:23 AM

I have this annoying problem: the fuel indicator on my 325i is not working, sowing empty all the time and the red light from it is on. The fuses are ok, the cables inside the dashboard are ok and plugged in corectly, and i wanted to check the fuel sensors (i don't know the technical name for those in english

, but i know how they look like and how they work

) inside the tank, but I don't know how to get to them. I took off the rear seat and i have (probably) 2 sensors, cause on the left side and also on the right side are 2 round robber disks mounted on the car body, having some wires which goes inside. If someone knows, are the fuel sensors there, and if yes, how can i remove them out for checking?

**3050rpm** · 05-09-2008, 01:46 PM

You might not have to go to all that trouble, this was a common problem with early E36s. This is what I was told by the technician at the dealer, and it's worked for me. Find the appropriate fuse for the indicator light on the dash (I'm not sure which one it is, maybe #21, but check) and remove it completely for 10 minutes. Reinsert and then see if your gauge starts working correctly. The fuse itself may look just fine, but just remove it for the period of time and take it from there. I hope that works for you.

**d3uterius** · 05-11-2008, 08:21 AM

So it could be a "software" problem? Hmmm... I'll check that tomorrow and come back with news. Thanks. I hope it works too..

**d3uterius** · 05-13-2008, 04:04 AM

3050rpm, it didn't work..The fuses for the instrument clusters are 23, 27, 31, 46 and for the illumination of instruments are 22, 26, 37. I took them out, all of them, because they don't say anywhere the exact scope of every fuse but no change. Thanks for the idea anyway..

I'm still waiting for ideas about the fuel sensors inside the fuel tank. Probably this weekend I'll try to broke them definitively...

)

**3050rpm** · 05-13-2008, 08:05 AM

I'm sorry to hear that, now that you listed all those fuses I believe it was #31, that would have been the simple fix. I imagine there was a TSB, technical service bulletin, on this, see if you can scare one up from a dealer or independent shop or, heaven forbid, from BMW of North America.

**d3uterius** · 05-19-2008, 01:22 AM

Over the weekend i got very annoyed about the fuel indicator and I tried again. It worked with the fuse #46, but only for a short period of time. Anyways, i think something is phisicaly broken, not only software. I'll try to clean the fuel sensors and also to check the dashboard instruments and come back with news.

**Alex 1993 525i auto** · 05-19-2008, 09:25 AM

I think you might check the fuel level sender. The fuel level sender has a built-in resistance that worn out over time. All is inside the trunk, under the carpet.

Hope it helps,
Alex

**3050rpm** · 05-19-2008, 11:27 AM

Again, sorry to hear that the simple approach didn't turn the trick, but maybe the previous posting gets to the heart of the matter. Should be a straightforward DIY job, just remember to disconnect the negative lead to the battery when working with an open gas tank, and be sure to have the code for your radio.

**d3uterius** · 05-21-2008, 12:36 AM

Thanks for the advice guys, i really appreciate it. It drove me on a straight line and now i know what i have to do,but i'm really freaked out about working with the fuel tank (had a scary experience few yers ago, but thanks God i don't have any scratch

)

I've made some researches and got some interesting information witch might help someone:

On the E36 325i coupe, the fuel senders (they are 2) are under the backseat.

The left fuel sender is a stand alone one,might have a fuel compensating siphon pump (models built up to 1995) and the right fuel sender is mounted on the fuel pump. The models built from 1995 have the fuel compensating siphon pump separately from the left fuel sender.After removing the cover, I'll have to disconnect the white plug on each sender unit, and before dismounting them from the fuel tank, first operation is to measure the resistance value. The values must be aproximately the same for the both units, and they are as follows:

Right Side Empty - 10-12 ohm

Left side Empty - 10-12 ohm

Right Side Full - 250-255 ohm

Left side Full - 250-255 ohm

The uel compensating siphon pump maintains the fuel level between the left and the right tank lobes.

You have here attached some sketches with the fuel tank and the fuel senders.

This weekend I'll start to dig and i will come back with news.

**Alex 1993 525i auto** · 05-21-2008, 11:33 PM

The good thing is that you don't need to open the fuel tank to test the sender, can be done by only removing harness and test resistance at the sender-pump electrical plug. The bad thing is if your test shows bad resistance, you have to remove the pump and sender to replace it :-)

**d3uterius** · 06-04-2008, 01:39 AM

I made the measurements yesterday, and the results are making me more confused...In the Bentley's Manual, tehy say that the value has to be between 10-12 ohm (empty) and 250-255 ohm (full), and I got this values:
Left side (driver side) 9.87 ohm
Right side 0 ohm

I know for sure that i have approx. 20 liters of fuel (from 65 total capacity)

More than probably, the right sender is dead. Gotta move to plan B - remove the senders.